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e767e0561d
mapping->tree_lock can be acquired from interrupt context. Then, following dead lock can occur. Assume "A" as a page. CPU0: lock_page_cgroup(A) interrupted -> take mapping->tree_lock. CPU1: take mapping->tree_lock -> lock_page_cgroup(A) This patch tries to fix above deadlock by moving memcg's hook to out of mapping->tree_lock. charge/uncharge of pagecache/swapcache is protected by page lock, not tree_lock. After this patch, lock_page_cgroup() is not called under mapping->tree_lock. Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2508 lines
66 KiB
C
2508 lines
66 KiB
C
/*
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* linux/mm/filemap.c
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*
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* Copyright (C) 1994-1999 Linus Torvalds
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*/
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/*
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* This file handles the generic file mmap semantics used by
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* most "normal" filesystems (but you don't /have/ to use this:
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* the NFS filesystem used to do this differently, for example)
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*/
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/compiler.h>
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#include <linux/fs.h>
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#include <linux/uaccess.h>
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#include <linux/aio.h>
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#include <linux/capability.h>
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#include <linux/kernel_stat.h>
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#include <linux/mm.h>
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#include <linux/swap.h>
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#include <linux/mman.h>
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#include <linux/pagemap.h>
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#include <linux/file.h>
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#include <linux/uio.h>
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#include <linux/hash.h>
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#include <linux/writeback.h>
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#include <linux/backing-dev.h>
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#include <linux/pagevec.h>
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#include <linux/blkdev.h>
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#include <linux/security.h>
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#include <linux/syscalls.h>
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#include <linux/cpuset.h>
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#include <linux/hardirq.h> /* for BUG_ON(!in_atomic()) only */
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#include <linux/memcontrol.h>
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#include <linux/mm_inline.h> /* for page_is_file_cache() */
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#include "internal.h"
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/*
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* FIXME: remove all knowledge of the buffer layer from the core VM
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*/
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#include <linux/buffer_head.h> /* for generic_osync_inode */
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#include <asm/mman.h>
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/*
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* Shared mappings implemented 30.11.1994. It's not fully working yet,
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* though.
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*
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* Shared mappings now work. 15.8.1995 Bruno.
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*
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* finished 'unifying' the page and buffer cache and SMP-threaded the
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* page-cache, 21.05.1999, Ingo Molnar <mingo@redhat.com>
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*
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* SMP-threaded pagemap-LRU 1999, Andrea Arcangeli <andrea@suse.de>
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*/
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/*
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* Lock ordering:
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*
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* ->i_mmap_lock (vmtruncate)
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* ->private_lock (__free_pte->__set_page_dirty_buffers)
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* ->swap_lock (exclusive_swap_page, others)
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* ->mapping->tree_lock
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*
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* ->i_mutex
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* ->i_mmap_lock (truncate->unmap_mapping_range)
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*
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* ->mmap_sem
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* ->i_mmap_lock
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* ->page_table_lock or pte_lock (various, mainly in memory.c)
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* ->mapping->tree_lock (arch-dependent flush_dcache_mmap_lock)
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*
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* ->mmap_sem
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* ->lock_page (access_process_vm)
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*
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* ->i_mutex (generic_file_buffered_write)
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* ->mmap_sem (fault_in_pages_readable->do_page_fault)
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*
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* ->i_mutex
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* ->i_alloc_sem (various)
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*
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* ->inode_lock
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* ->sb_lock (fs/fs-writeback.c)
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* ->mapping->tree_lock (__sync_single_inode)
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*
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* ->i_mmap_lock
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* ->anon_vma.lock (vma_adjust)
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*
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* ->anon_vma.lock
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* ->page_table_lock or pte_lock (anon_vma_prepare and various)
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*
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* ->page_table_lock or pte_lock
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* ->swap_lock (try_to_unmap_one)
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* ->private_lock (try_to_unmap_one)
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* ->tree_lock (try_to_unmap_one)
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* ->zone.lru_lock (follow_page->mark_page_accessed)
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* ->zone.lru_lock (check_pte_range->isolate_lru_page)
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* ->private_lock (page_remove_rmap->set_page_dirty)
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* ->tree_lock (page_remove_rmap->set_page_dirty)
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* ->inode_lock (page_remove_rmap->set_page_dirty)
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* ->inode_lock (zap_pte_range->set_page_dirty)
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* ->private_lock (zap_pte_range->__set_page_dirty_buffers)
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*
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* ->task->proc_lock
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* ->dcache_lock (proc_pid_lookup)
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*/
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/*
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* Remove a page from the page cache and free it. Caller has to make
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* sure the page is locked and that nobody else uses it - or that usage
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* is safe. The caller must hold the mapping's tree_lock.
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*/
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void __remove_from_page_cache(struct page *page)
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{
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struct address_space *mapping = page->mapping;
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radix_tree_delete(&mapping->page_tree, page->index);
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page->mapping = NULL;
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mapping->nrpages--;
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__dec_zone_page_state(page, NR_FILE_PAGES);
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BUG_ON(page_mapped(page));
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/*
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* Some filesystems seem to re-dirty the page even after
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* the VM has canceled the dirty bit (eg ext3 journaling).
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*
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* Fix it up by doing a final dirty accounting check after
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* having removed the page entirely.
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*/
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if (PageDirty(page) && mapping_cap_account_dirty(mapping)) {
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dec_zone_page_state(page, NR_FILE_DIRTY);
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dec_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE);
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}
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}
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void remove_from_page_cache(struct page *page)
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{
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struct address_space *mapping = page->mapping;
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BUG_ON(!PageLocked(page));
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spin_lock_irq(&mapping->tree_lock);
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__remove_from_page_cache(page);
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spin_unlock_irq(&mapping->tree_lock);
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mem_cgroup_uncharge_cache_page(page);
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}
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static int sync_page(void *word)
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{
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struct address_space *mapping;
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struct page *page;
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page = container_of((unsigned long *)word, struct page, flags);
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/*
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* page_mapping() is being called without PG_locked held.
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* Some knowledge of the state and use of the page is used to
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* reduce the requirements down to a memory barrier.
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* The danger here is of a stale page_mapping() return value
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* indicating a struct address_space different from the one it's
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* associated with when it is associated with one.
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* After smp_mb(), it's either the correct page_mapping() for
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* the page, or an old page_mapping() and the page's own
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* page_mapping() has gone NULL.
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* The ->sync_page() address_space operation must tolerate
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* page_mapping() going NULL. By an amazing coincidence,
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* this comes about because none of the users of the page
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* in the ->sync_page() methods make essential use of the
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* page_mapping(), merely passing the page down to the backing
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* device's unplug functions when it's non-NULL, which in turn
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* ignore it for all cases but swap, where only page_private(page) is
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* of interest. When page_mapping() does go NULL, the entire
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* call stack gracefully ignores the page and returns.
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* -- wli
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*/
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smp_mb();
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mapping = page_mapping(page);
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if (mapping && mapping->a_ops && mapping->a_ops->sync_page)
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mapping->a_ops->sync_page(page);
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io_schedule();
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return 0;
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}
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static int sync_page_killable(void *word)
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{
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sync_page(word);
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return fatal_signal_pending(current) ? -EINTR : 0;
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}
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/**
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* __filemap_fdatawrite_range - start writeback on mapping dirty pages in range
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* @mapping: address space structure to write
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* @start: offset in bytes where the range starts
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* @end: offset in bytes where the range ends (inclusive)
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* @sync_mode: enable synchronous operation
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*
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* Start writeback against all of a mapping's dirty pages that lie
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* within the byte offsets <start, end> inclusive.
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*
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* If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as
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* opposed to a regular memory cleansing writeback. The difference between
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* these two operations is that if a dirty page/buffer is encountered, it must
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* be waited upon, and not just skipped over.
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*/
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int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
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loff_t end, int sync_mode)
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{
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int ret;
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struct writeback_control wbc = {
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.sync_mode = sync_mode,
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.nr_to_write = LONG_MAX,
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.range_start = start,
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.range_end = end,
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};
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if (!mapping_cap_writeback_dirty(mapping))
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return 0;
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ret = do_writepages(mapping, &wbc);
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return ret;
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}
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static inline int __filemap_fdatawrite(struct address_space *mapping,
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int sync_mode)
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{
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return __filemap_fdatawrite_range(mapping, 0, LLONG_MAX, sync_mode);
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}
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int filemap_fdatawrite(struct address_space *mapping)
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{
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return __filemap_fdatawrite(mapping, WB_SYNC_ALL);
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}
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EXPORT_SYMBOL(filemap_fdatawrite);
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int filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
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loff_t end)
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{
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return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL);
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}
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EXPORT_SYMBOL(filemap_fdatawrite_range);
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/**
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* filemap_flush - mostly a non-blocking flush
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* @mapping: target address_space
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*
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* This is a mostly non-blocking flush. Not suitable for data-integrity
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* purposes - I/O may not be started against all dirty pages.
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*/
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int filemap_flush(struct address_space *mapping)
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{
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return __filemap_fdatawrite(mapping, WB_SYNC_NONE);
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}
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EXPORT_SYMBOL(filemap_flush);
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/**
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* wait_on_page_writeback_range - wait for writeback to complete
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* @mapping: target address_space
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* @start: beginning page index
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* @end: ending page index
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*
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* Wait for writeback to complete against pages indexed by start->end
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* inclusive
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*/
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int wait_on_page_writeback_range(struct address_space *mapping,
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pgoff_t start, pgoff_t end)
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{
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struct pagevec pvec;
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int nr_pages;
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int ret = 0;
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pgoff_t index;
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if (end < start)
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return 0;
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pagevec_init(&pvec, 0);
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index = start;
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while ((index <= end) &&
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(nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
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PAGECACHE_TAG_WRITEBACK,
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min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) {
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unsigned i;
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for (i = 0; i < nr_pages; i++) {
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struct page *page = pvec.pages[i];
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/* until radix tree lookup accepts end_index */
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if (page->index > end)
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continue;
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wait_on_page_writeback(page);
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if (PageError(page))
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ret = -EIO;
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}
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pagevec_release(&pvec);
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cond_resched();
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}
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/* Check for outstanding write errors */
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if (test_and_clear_bit(AS_ENOSPC, &mapping->flags))
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ret = -ENOSPC;
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if (test_and_clear_bit(AS_EIO, &mapping->flags))
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ret = -EIO;
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return ret;
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}
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/**
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* sync_page_range - write and wait on all pages in the passed range
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* @inode: target inode
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* @mapping: target address_space
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* @pos: beginning offset in pages to write
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* @count: number of bytes to write
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*
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* Write and wait upon all the pages in the passed range. This is a "data
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* integrity" operation. It waits upon in-flight writeout before starting and
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* waiting upon new writeout. If there was an IO error, return it.
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*
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* We need to re-take i_mutex during the generic_osync_inode list walk because
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* it is otherwise livelockable.
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*/
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int sync_page_range(struct inode *inode, struct address_space *mapping,
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loff_t pos, loff_t count)
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{
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pgoff_t start = pos >> PAGE_CACHE_SHIFT;
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pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT;
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int ret;
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if (!mapping_cap_writeback_dirty(mapping) || !count)
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return 0;
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ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1);
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if (ret == 0) {
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mutex_lock(&inode->i_mutex);
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ret = generic_osync_inode(inode, mapping, OSYNC_METADATA);
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mutex_unlock(&inode->i_mutex);
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}
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if (ret == 0)
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ret = wait_on_page_writeback_range(mapping, start, end);
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return ret;
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}
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EXPORT_SYMBOL(sync_page_range);
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/**
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* sync_page_range_nolock - write & wait on all pages in the passed range without locking
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* @inode: target inode
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* @mapping: target address_space
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* @pos: beginning offset in pages to write
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* @count: number of bytes to write
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*
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* Note: Holding i_mutex across sync_page_range_nolock() is not a good idea
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* as it forces O_SYNC writers to different parts of the same file
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* to be serialised right until io completion.
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*/
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int sync_page_range_nolock(struct inode *inode, struct address_space *mapping,
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loff_t pos, loff_t count)
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{
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pgoff_t start = pos >> PAGE_CACHE_SHIFT;
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pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT;
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int ret;
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if (!mapping_cap_writeback_dirty(mapping) || !count)
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return 0;
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ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1);
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if (ret == 0)
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ret = generic_osync_inode(inode, mapping, OSYNC_METADATA);
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if (ret == 0)
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ret = wait_on_page_writeback_range(mapping, start, end);
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return ret;
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}
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EXPORT_SYMBOL(sync_page_range_nolock);
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/**
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* filemap_fdatawait - wait for all under-writeback pages to complete
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* @mapping: address space structure to wait for
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*
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* Walk the list of under-writeback pages of the given address space
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* and wait for all of them.
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*/
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int filemap_fdatawait(struct address_space *mapping)
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{
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loff_t i_size = i_size_read(mapping->host);
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if (i_size == 0)
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return 0;
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return wait_on_page_writeback_range(mapping, 0,
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(i_size - 1) >> PAGE_CACHE_SHIFT);
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}
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EXPORT_SYMBOL(filemap_fdatawait);
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int filemap_write_and_wait(struct address_space *mapping)
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{
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int err = 0;
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|
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if (mapping->nrpages) {
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err = filemap_fdatawrite(mapping);
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/*
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* Even if the above returned error, the pages may be
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* written partially (e.g. -ENOSPC), so we wait for it.
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* But the -EIO is special case, it may indicate the worst
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* thing (e.g. bug) happened, so we avoid waiting for it.
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*/
|
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if (err != -EIO) {
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int err2 = filemap_fdatawait(mapping);
|
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if (!err)
|
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err = err2;
|
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}
|
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}
|
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return err;
|
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}
|
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EXPORT_SYMBOL(filemap_write_and_wait);
|
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|
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/**
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* filemap_write_and_wait_range - write out & wait on a file range
|
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* @mapping: the address_space for the pages
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* @lstart: offset in bytes where the range starts
|
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* @lend: offset in bytes where the range ends (inclusive)
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*
|
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* Write out and wait upon file offsets lstart->lend, inclusive.
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*
|
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* Note that `lend' is inclusive (describes the last byte to be written) so
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* that this function can be used to write to the very end-of-file (end = -1).
|
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*/
|
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int filemap_write_and_wait_range(struct address_space *mapping,
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loff_t lstart, loff_t lend)
|
|
{
|
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int err = 0;
|
|
|
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if (mapping->nrpages) {
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err = __filemap_fdatawrite_range(mapping, lstart, lend,
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WB_SYNC_ALL);
|
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/* See comment of filemap_write_and_wait() */
|
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if (err != -EIO) {
|
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int err2 = wait_on_page_writeback_range(mapping,
|
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lstart >> PAGE_CACHE_SHIFT,
|
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lend >> PAGE_CACHE_SHIFT);
|
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if (!err)
|
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err = err2;
|
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}
|
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}
|
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return err;
|
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}
|
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EXPORT_SYMBOL(filemap_write_and_wait_range);
|
|
|
|
/**
|
|
* add_to_page_cache_locked - add a locked page to the pagecache
|
|
* @page: page to add
|
|
* @mapping: the page's address_space
|
|
* @offset: page index
|
|
* @gfp_mask: page allocation mode
|
|
*
|
|
* This function is used to add a page to the pagecache. It must be locked.
|
|
* This function does not add the page to the LRU. The caller must do that.
|
|
*/
|
|
int add_to_page_cache_locked(struct page *page, struct address_space *mapping,
|
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pgoff_t offset, gfp_t gfp_mask)
|
|
{
|
|
int error;
|
|
|
|
VM_BUG_ON(!PageLocked(page));
|
|
|
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error = mem_cgroup_cache_charge(page, current->mm,
|
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gfp_mask & GFP_RECLAIM_MASK);
|
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if (error)
|
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goto out;
|
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|
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error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM);
|
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if (error == 0) {
|
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page_cache_get(page);
|
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page->mapping = mapping;
|
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page->index = offset;
|
|
|
|
spin_lock_irq(&mapping->tree_lock);
|
|
error = radix_tree_insert(&mapping->page_tree, offset, page);
|
|
if (likely(!error)) {
|
|
mapping->nrpages++;
|
|
__inc_zone_page_state(page, NR_FILE_PAGES);
|
|
spin_unlock_irq(&mapping->tree_lock);
|
|
} else {
|
|
page->mapping = NULL;
|
|
spin_unlock_irq(&mapping->tree_lock);
|
|
mem_cgroup_uncharge_cache_page(page);
|
|
page_cache_release(page);
|
|
}
|
|
radix_tree_preload_end();
|
|
} else
|
|
mem_cgroup_uncharge_cache_page(page);
|
|
out:
|
|
return error;
|
|
}
|
|
EXPORT_SYMBOL(add_to_page_cache_locked);
|
|
|
|
int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
|
|
pgoff_t offset, gfp_t gfp_mask)
|
|
{
|
|
int ret;
|
|
|
|
/*
|
|
* Splice_read and readahead add shmem/tmpfs pages into the page cache
|
|
* before shmem_readpage has a chance to mark them as SwapBacked: they
|
|
* need to go on the active_anon lru below, and mem_cgroup_cache_charge
|
|
* (called in add_to_page_cache) needs to know where they're going too.
|
|
*/
|
|
if (mapping_cap_swap_backed(mapping))
|
|
SetPageSwapBacked(page);
|
|
|
|
ret = add_to_page_cache(page, mapping, offset, gfp_mask);
|
|
if (ret == 0) {
|
|
if (page_is_file_cache(page))
|
|
lru_cache_add_file(page);
|
|
else
|
|
lru_cache_add_active_anon(page);
|
|
}
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(add_to_page_cache_lru);
|
|
|
|
#ifdef CONFIG_NUMA
|
|
struct page *__page_cache_alloc(gfp_t gfp)
|
|
{
|
|
if (cpuset_do_page_mem_spread()) {
|
|
int n = cpuset_mem_spread_node();
|
|
return alloc_pages_node(n, gfp, 0);
|
|
}
|
|
return alloc_pages(gfp, 0);
|
|
}
|
|
EXPORT_SYMBOL(__page_cache_alloc);
|
|
#endif
|
|
|
|
static int __sleep_on_page_lock(void *word)
|
|
{
|
|
io_schedule();
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* In order to wait for pages to become available there must be
|
|
* waitqueues associated with pages. By using a hash table of
|
|
* waitqueues where the bucket discipline is to maintain all
|
|
* waiters on the same queue and wake all when any of the pages
|
|
* become available, and for the woken contexts to check to be
|
|
* sure the appropriate page became available, this saves space
|
|
* at a cost of "thundering herd" phenomena during rare hash
|
|
* collisions.
|
|
*/
|
|
static wait_queue_head_t *page_waitqueue(struct page *page)
|
|
{
|
|
const struct zone *zone = page_zone(page);
|
|
|
|
return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)];
|
|
}
|
|
|
|
static inline void wake_up_page(struct page *page, int bit)
|
|
{
|
|
__wake_up_bit(page_waitqueue(page), &page->flags, bit);
|
|
}
|
|
|
|
void wait_on_page_bit(struct page *page, int bit_nr)
|
|
{
|
|
DEFINE_WAIT_BIT(wait, &page->flags, bit_nr);
|
|
|
|
if (test_bit(bit_nr, &page->flags))
|
|
__wait_on_bit(page_waitqueue(page), &wait, sync_page,
|
|
TASK_UNINTERRUPTIBLE);
|
|
}
|
|
EXPORT_SYMBOL(wait_on_page_bit);
|
|
|
|
/**
|
|
* add_page_wait_queue - Add an arbitrary waiter to a page's wait queue
|
|
* @page: Page defining the wait queue of interest
|
|
* @waiter: Waiter to add to the queue
|
|
*
|
|
* Add an arbitrary @waiter to the wait queue for the nominated @page.
|
|
*/
|
|
void add_page_wait_queue(struct page *page, wait_queue_t *waiter)
|
|
{
|
|
wait_queue_head_t *q = page_waitqueue(page);
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&q->lock, flags);
|
|
__add_wait_queue(q, waiter);
|
|
spin_unlock_irqrestore(&q->lock, flags);
|
|
}
|
|
EXPORT_SYMBOL_GPL(add_page_wait_queue);
|
|
|
|
/**
|
|
* unlock_page - unlock a locked page
|
|
* @page: the page
|
|
*
|
|
* Unlocks the page and wakes up sleepers in ___wait_on_page_locked().
|
|
* Also wakes sleepers in wait_on_page_writeback() because the wakeup
|
|
* mechananism between PageLocked pages and PageWriteback pages is shared.
|
|
* But that's OK - sleepers in wait_on_page_writeback() just go back to sleep.
|
|
*
|
|
* The mb is necessary to enforce ordering between the clear_bit and the read
|
|
* of the waitqueue (to avoid SMP races with a parallel wait_on_page_locked()).
|
|
*/
|
|
void unlock_page(struct page *page)
|
|
{
|
|
VM_BUG_ON(!PageLocked(page));
|
|
clear_bit_unlock(PG_locked, &page->flags);
|
|
smp_mb__after_clear_bit();
|
|
wake_up_page(page, PG_locked);
|
|
}
|
|
EXPORT_SYMBOL(unlock_page);
|
|
|
|
/**
|
|
* end_page_writeback - end writeback against a page
|
|
* @page: the page
|
|
*/
|
|
void end_page_writeback(struct page *page)
|
|
{
|
|
if (TestClearPageReclaim(page))
|
|
rotate_reclaimable_page(page);
|
|
|
|
if (!test_clear_page_writeback(page))
|
|
BUG();
|
|
|
|
smp_mb__after_clear_bit();
|
|
wake_up_page(page, PG_writeback);
|
|
}
|
|
EXPORT_SYMBOL(end_page_writeback);
|
|
|
|
/**
|
|
* __lock_page - get a lock on the page, assuming we need to sleep to get it
|
|
* @page: the page to lock
|
|
*
|
|
* Ugly. Running sync_page() in state TASK_UNINTERRUPTIBLE is scary. If some
|
|
* random driver's requestfn sets TASK_RUNNING, we could busywait. However
|
|
* chances are that on the second loop, the block layer's plug list is empty,
|
|
* so sync_page() will then return in state TASK_UNINTERRUPTIBLE.
|
|
*/
|
|
void __lock_page(struct page *page)
|
|
{
|
|
DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
|
|
|
|
__wait_on_bit_lock(page_waitqueue(page), &wait, sync_page,
|
|
TASK_UNINTERRUPTIBLE);
|
|
}
|
|
EXPORT_SYMBOL(__lock_page);
|
|
|
|
int __lock_page_killable(struct page *page)
|
|
{
|
|
DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
|
|
|
|
return __wait_on_bit_lock(page_waitqueue(page), &wait,
|
|
sync_page_killable, TASK_KILLABLE);
|
|
}
|
|
EXPORT_SYMBOL_GPL(__lock_page_killable);
|
|
|
|
/**
|
|
* __lock_page_nosync - get a lock on the page, without calling sync_page()
|
|
* @page: the page to lock
|
|
*
|
|
* Variant of lock_page that does not require the caller to hold a reference
|
|
* on the page's mapping.
|
|
*/
|
|
void __lock_page_nosync(struct page *page)
|
|
{
|
|
DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
|
|
__wait_on_bit_lock(page_waitqueue(page), &wait, __sleep_on_page_lock,
|
|
TASK_UNINTERRUPTIBLE);
|
|
}
|
|
|
|
/**
|
|
* find_get_page - find and get a page reference
|
|
* @mapping: the address_space to search
|
|
* @offset: the page index
|
|
*
|
|
* Is there a pagecache struct page at the given (mapping, offset) tuple?
|
|
* If yes, increment its refcount and return it; if no, return NULL.
|
|
*/
|
|
struct page *find_get_page(struct address_space *mapping, pgoff_t offset)
|
|
{
|
|
void **pagep;
|
|
struct page *page;
|
|
|
|
rcu_read_lock();
|
|
repeat:
|
|
page = NULL;
|
|
pagep = radix_tree_lookup_slot(&mapping->page_tree, offset);
|
|
if (pagep) {
|
|
page = radix_tree_deref_slot(pagep);
|
|
if (unlikely(!page || page == RADIX_TREE_RETRY))
|
|
goto repeat;
|
|
|
|
if (!page_cache_get_speculative(page))
|
|
goto repeat;
|
|
|
|
/*
|
|
* Has the page moved?
|
|
* This is part of the lockless pagecache protocol. See
|
|
* include/linux/pagemap.h for details.
|
|
*/
|
|
if (unlikely(page != *pagep)) {
|
|
page_cache_release(page);
|
|
goto repeat;
|
|
}
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
return page;
|
|
}
|
|
EXPORT_SYMBOL(find_get_page);
|
|
|
|
/**
|
|
* find_lock_page - locate, pin and lock a pagecache page
|
|
* @mapping: the address_space to search
|
|
* @offset: the page index
|
|
*
|
|
* Locates the desired pagecache page, locks it, increments its reference
|
|
* count and returns its address.
|
|
*
|
|
* Returns zero if the page was not present. find_lock_page() may sleep.
|
|
*/
|
|
struct page *find_lock_page(struct address_space *mapping, pgoff_t offset)
|
|
{
|
|
struct page *page;
|
|
|
|
repeat:
|
|
page = find_get_page(mapping, offset);
|
|
if (page) {
|
|
lock_page(page);
|
|
/* Has the page been truncated? */
|
|
if (unlikely(page->mapping != mapping)) {
|
|
unlock_page(page);
|
|
page_cache_release(page);
|
|
goto repeat;
|
|
}
|
|
VM_BUG_ON(page->index != offset);
|
|
}
|
|
return page;
|
|
}
|
|
EXPORT_SYMBOL(find_lock_page);
|
|
|
|
/**
|
|
* find_or_create_page - locate or add a pagecache page
|
|
* @mapping: the page's address_space
|
|
* @index: the page's index into the mapping
|
|
* @gfp_mask: page allocation mode
|
|
*
|
|
* Locates a page in the pagecache. If the page is not present, a new page
|
|
* is allocated using @gfp_mask and is added to the pagecache and to the VM's
|
|
* LRU list. The returned page is locked and has its reference count
|
|
* incremented.
|
|
*
|
|
* find_or_create_page() may sleep, even if @gfp_flags specifies an atomic
|
|
* allocation!
|
|
*
|
|
* find_or_create_page() returns the desired page's address, or zero on
|
|
* memory exhaustion.
|
|
*/
|
|
struct page *find_or_create_page(struct address_space *mapping,
|
|
pgoff_t index, gfp_t gfp_mask)
|
|
{
|
|
struct page *page;
|
|
int err;
|
|
repeat:
|
|
page = find_lock_page(mapping, index);
|
|
if (!page) {
|
|
page = __page_cache_alloc(gfp_mask);
|
|
if (!page)
|
|
return NULL;
|
|
/*
|
|
* We want a regular kernel memory (not highmem or DMA etc)
|
|
* allocation for the radix tree nodes, but we need to honour
|
|
* the context-specific requirements the caller has asked for.
|
|
* GFP_RECLAIM_MASK collects those requirements.
|
|
*/
|
|
err = add_to_page_cache_lru(page, mapping, index,
|
|
(gfp_mask & GFP_RECLAIM_MASK));
|
|
if (unlikely(err)) {
|
|
page_cache_release(page);
|
|
page = NULL;
|
|
if (err == -EEXIST)
|
|
goto repeat;
|
|
}
|
|
}
|
|
return page;
|
|
}
|
|
EXPORT_SYMBOL(find_or_create_page);
|
|
|
|
/**
|
|
* find_get_pages - gang pagecache lookup
|
|
* @mapping: The address_space to search
|
|
* @start: The starting page index
|
|
* @nr_pages: The maximum number of pages
|
|
* @pages: Where the resulting pages are placed
|
|
*
|
|
* find_get_pages() will search for and return a group of up to
|
|
* @nr_pages pages in the mapping. The pages are placed at @pages.
|
|
* find_get_pages() takes a reference against the returned pages.
|
|
*
|
|
* The search returns a group of mapping-contiguous pages with ascending
|
|
* indexes. There may be holes in the indices due to not-present pages.
|
|
*
|
|
* find_get_pages() returns the number of pages which were found.
|
|
*/
|
|
unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
|
|
unsigned int nr_pages, struct page **pages)
|
|
{
|
|
unsigned int i;
|
|
unsigned int ret;
|
|
unsigned int nr_found;
|
|
|
|
rcu_read_lock();
|
|
restart:
|
|
nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree,
|
|
(void ***)pages, start, nr_pages);
|
|
ret = 0;
|
|
for (i = 0; i < nr_found; i++) {
|
|
struct page *page;
|
|
repeat:
|
|
page = radix_tree_deref_slot((void **)pages[i]);
|
|
if (unlikely(!page))
|
|
continue;
|
|
/*
|
|
* this can only trigger if nr_found == 1, making livelock
|
|
* a non issue.
|
|
*/
|
|
if (unlikely(page == RADIX_TREE_RETRY))
|
|
goto restart;
|
|
|
|
if (!page_cache_get_speculative(page))
|
|
goto repeat;
|
|
|
|
/* Has the page moved? */
|
|
if (unlikely(page != *((void **)pages[i]))) {
|
|
page_cache_release(page);
|
|
goto repeat;
|
|
}
|
|
|
|
pages[ret] = page;
|
|
ret++;
|
|
}
|
|
rcu_read_unlock();
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* find_get_pages_contig - gang contiguous pagecache lookup
|
|
* @mapping: The address_space to search
|
|
* @index: The starting page index
|
|
* @nr_pages: The maximum number of pages
|
|
* @pages: Where the resulting pages are placed
|
|
*
|
|
* find_get_pages_contig() works exactly like find_get_pages(), except
|
|
* that the returned number of pages are guaranteed to be contiguous.
|
|
*
|
|
* find_get_pages_contig() returns the number of pages which were found.
|
|
*/
|
|
unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,
|
|
unsigned int nr_pages, struct page **pages)
|
|
{
|
|
unsigned int i;
|
|
unsigned int ret;
|
|
unsigned int nr_found;
|
|
|
|
rcu_read_lock();
|
|
restart:
|
|
nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree,
|
|
(void ***)pages, index, nr_pages);
|
|
ret = 0;
|
|
for (i = 0; i < nr_found; i++) {
|
|
struct page *page;
|
|
repeat:
|
|
page = radix_tree_deref_slot((void **)pages[i]);
|
|
if (unlikely(!page))
|
|
continue;
|
|
/*
|
|
* this can only trigger if nr_found == 1, making livelock
|
|
* a non issue.
|
|
*/
|
|
if (unlikely(page == RADIX_TREE_RETRY))
|
|
goto restart;
|
|
|
|
if (page->mapping == NULL || page->index != index)
|
|
break;
|
|
|
|
if (!page_cache_get_speculative(page))
|
|
goto repeat;
|
|
|
|
/* Has the page moved? */
|
|
if (unlikely(page != *((void **)pages[i]))) {
|
|
page_cache_release(page);
|
|
goto repeat;
|
|
}
|
|
|
|
pages[ret] = page;
|
|
ret++;
|
|
index++;
|
|
}
|
|
rcu_read_unlock();
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(find_get_pages_contig);
|
|
|
|
/**
|
|
* find_get_pages_tag - find and return pages that match @tag
|
|
* @mapping: the address_space to search
|
|
* @index: the starting page index
|
|
* @tag: the tag index
|
|
* @nr_pages: the maximum number of pages
|
|
* @pages: where the resulting pages are placed
|
|
*
|
|
* Like find_get_pages, except we only return pages which are tagged with
|
|
* @tag. We update @index to index the next page for the traversal.
|
|
*/
|
|
unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
|
|
int tag, unsigned int nr_pages, struct page **pages)
|
|
{
|
|
unsigned int i;
|
|
unsigned int ret;
|
|
unsigned int nr_found;
|
|
|
|
rcu_read_lock();
|
|
restart:
|
|
nr_found = radix_tree_gang_lookup_tag_slot(&mapping->page_tree,
|
|
(void ***)pages, *index, nr_pages, tag);
|
|
ret = 0;
|
|
for (i = 0; i < nr_found; i++) {
|
|
struct page *page;
|
|
repeat:
|
|
page = radix_tree_deref_slot((void **)pages[i]);
|
|
if (unlikely(!page))
|
|
continue;
|
|
/*
|
|
* this can only trigger if nr_found == 1, making livelock
|
|
* a non issue.
|
|
*/
|
|
if (unlikely(page == RADIX_TREE_RETRY))
|
|
goto restart;
|
|
|
|
if (!page_cache_get_speculative(page))
|
|
goto repeat;
|
|
|
|
/* Has the page moved? */
|
|
if (unlikely(page != *((void **)pages[i]))) {
|
|
page_cache_release(page);
|
|
goto repeat;
|
|
}
|
|
|
|
pages[ret] = page;
|
|
ret++;
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
if (ret)
|
|
*index = pages[ret - 1]->index + 1;
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(find_get_pages_tag);
|
|
|
|
/**
|
|
* grab_cache_page_nowait - returns locked page at given index in given cache
|
|
* @mapping: target address_space
|
|
* @index: the page index
|
|
*
|
|
* Same as grab_cache_page(), but do not wait if the page is unavailable.
|
|
* This is intended for speculative data generators, where the data can
|
|
* be regenerated if the page couldn't be grabbed. This routine should
|
|
* be safe to call while holding the lock for another page.
|
|
*
|
|
* Clear __GFP_FS when allocating the page to avoid recursion into the fs
|
|
* and deadlock against the caller's locked page.
|
|
*/
|
|
struct page *
|
|
grab_cache_page_nowait(struct address_space *mapping, pgoff_t index)
|
|
{
|
|
struct page *page = find_get_page(mapping, index);
|
|
|
|
if (page) {
|
|
if (trylock_page(page))
|
|
return page;
|
|
page_cache_release(page);
|
|
return NULL;
|
|
}
|
|
page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~__GFP_FS);
|
|
if (page && add_to_page_cache_lru(page, mapping, index, GFP_NOFS)) {
|
|
page_cache_release(page);
|
|
page = NULL;
|
|
}
|
|
return page;
|
|
}
|
|
EXPORT_SYMBOL(grab_cache_page_nowait);
|
|
|
|
/*
|
|
* CD/DVDs are error prone. When a medium error occurs, the driver may fail
|
|
* a _large_ part of the i/o request. Imagine the worst scenario:
|
|
*
|
|
* ---R__________________________________________B__________
|
|
* ^ reading here ^ bad block(assume 4k)
|
|
*
|
|
* read(R) => miss => readahead(R...B) => media error => frustrating retries
|
|
* => failing the whole request => read(R) => read(R+1) =>
|
|
* readahead(R+1...B+1) => bang => read(R+2) => read(R+3) =>
|
|
* readahead(R+3...B+2) => bang => read(R+3) => read(R+4) =>
|
|
* readahead(R+4...B+3) => bang => read(R+4) => read(R+5) => ......
|
|
*
|
|
* It is going insane. Fix it by quickly scaling down the readahead size.
|
|
*/
|
|
static void shrink_readahead_size_eio(struct file *filp,
|
|
struct file_ra_state *ra)
|
|
{
|
|
if (!ra->ra_pages)
|
|
return;
|
|
|
|
ra->ra_pages /= 4;
|
|
}
|
|
|
|
/**
|
|
* do_generic_file_read - generic file read routine
|
|
* @filp: the file to read
|
|
* @ppos: current file position
|
|
* @desc: read_descriptor
|
|
* @actor: read method
|
|
*
|
|
* This is a generic file read routine, and uses the
|
|
* mapping->a_ops->readpage() function for the actual low-level stuff.
|
|
*
|
|
* This is really ugly. But the goto's actually try to clarify some
|
|
* of the logic when it comes to error handling etc.
|
|
*/
|
|
static void do_generic_file_read(struct file *filp, loff_t *ppos,
|
|
read_descriptor_t *desc, read_actor_t actor)
|
|
{
|
|
struct address_space *mapping = filp->f_mapping;
|
|
struct inode *inode = mapping->host;
|
|
struct file_ra_state *ra = &filp->f_ra;
|
|
pgoff_t index;
|
|
pgoff_t last_index;
|
|
pgoff_t prev_index;
|
|
unsigned long offset; /* offset into pagecache page */
|
|
unsigned int prev_offset;
|
|
int error;
|
|
|
|
index = *ppos >> PAGE_CACHE_SHIFT;
|
|
prev_index = ra->prev_pos >> PAGE_CACHE_SHIFT;
|
|
prev_offset = ra->prev_pos & (PAGE_CACHE_SIZE-1);
|
|
last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
|
|
offset = *ppos & ~PAGE_CACHE_MASK;
|
|
|
|
for (;;) {
|
|
struct page *page;
|
|
pgoff_t end_index;
|
|
loff_t isize;
|
|
unsigned long nr, ret;
|
|
|
|
cond_resched();
|
|
find_page:
|
|
page = find_get_page(mapping, index);
|
|
if (!page) {
|
|
page_cache_sync_readahead(mapping,
|
|
ra, filp,
|
|
index, last_index - index);
|
|
page = find_get_page(mapping, index);
|
|
if (unlikely(page == NULL))
|
|
goto no_cached_page;
|
|
}
|
|
if (PageReadahead(page)) {
|
|
page_cache_async_readahead(mapping,
|
|
ra, filp, page,
|
|
index, last_index - index);
|
|
}
|
|
if (!PageUptodate(page)) {
|
|
if (inode->i_blkbits == PAGE_CACHE_SHIFT ||
|
|
!mapping->a_ops->is_partially_uptodate)
|
|
goto page_not_up_to_date;
|
|
if (!trylock_page(page))
|
|
goto page_not_up_to_date;
|
|
if (!mapping->a_ops->is_partially_uptodate(page,
|
|
desc, offset))
|
|
goto page_not_up_to_date_locked;
|
|
unlock_page(page);
|
|
}
|
|
page_ok:
|
|
/*
|
|
* i_size must be checked after we know the page is Uptodate.
|
|
*
|
|
* Checking i_size after the check allows us to calculate
|
|
* the correct value for "nr", which means the zero-filled
|
|
* part of the page is not copied back to userspace (unless
|
|
* another truncate extends the file - this is desired though).
|
|
*/
|
|
|
|
isize = i_size_read(inode);
|
|
end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
|
|
if (unlikely(!isize || index > end_index)) {
|
|
page_cache_release(page);
|
|
goto out;
|
|
}
|
|
|
|
/* nr is the maximum number of bytes to copy from this page */
|
|
nr = PAGE_CACHE_SIZE;
|
|
if (index == end_index) {
|
|
nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
|
|
if (nr <= offset) {
|
|
page_cache_release(page);
|
|
goto out;
|
|
}
|
|
}
|
|
nr = nr - offset;
|
|
|
|
/* If users can be writing to this page using arbitrary
|
|
* virtual addresses, take care about potential aliasing
|
|
* before reading the page on the kernel side.
|
|
*/
|
|
if (mapping_writably_mapped(mapping))
|
|
flush_dcache_page(page);
|
|
|
|
/*
|
|
* When a sequential read accesses a page several times,
|
|
* only mark it as accessed the first time.
|
|
*/
|
|
if (prev_index != index || offset != prev_offset)
|
|
mark_page_accessed(page);
|
|
prev_index = index;
|
|
|
|
/*
|
|
* Ok, we have the page, and it's up-to-date, so
|
|
* now we can copy it to user space...
|
|
*
|
|
* The actor routine returns how many bytes were actually used..
|
|
* NOTE! This may not be the same as how much of a user buffer
|
|
* we filled up (we may be padding etc), so we can only update
|
|
* "pos" here (the actor routine has to update the user buffer
|
|
* pointers and the remaining count).
|
|
*/
|
|
ret = actor(desc, page, offset, nr);
|
|
offset += ret;
|
|
index += offset >> PAGE_CACHE_SHIFT;
|
|
offset &= ~PAGE_CACHE_MASK;
|
|
prev_offset = offset;
|
|
|
|
page_cache_release(page);
|
|
if (ret == nr && desc->count)
|
|
continue;
|
|
goto out;
|
|
|
|
page_not_up_to_date:
|
|
/* Get exclusive access to the page ... */
|
|
error = lock_page_killable(page);
|
|
if (unlikely(error))
|
|
goto readpage_error;
|
|
|
|
page_not_up_to_date_locked:
|
|
/* Did it get truncated before we got the lock? */
|
|
if (!page->mapping) {
|
|
unlock_page(page);
|
|
page_cache_release(page);
|
|
continue;
|
|
}
|
|
|
|
/* Did somebody else fill it already? */
|
|
if (PageUptodate(page)) {
|
|
unlock_page(page);
|
|
goto page_ok;
|
|
}
|
|
|
|
readpage:
|
|
/* Start the actual read. The read will unlock the page. */
|
|
error = mapping->a_ops->readpage(filp, page);
|
|
|
|
if (unlikely(error)) {
|
|
if (error == AOP_TRUNCATED_PAGE) {
|
|
page_cache_release(page);
|
|
goto find_page;
|
|
}
|
|
goto readpage_error;
|
|
}
|
|
|
|
if (!PageUptodate(page)) {
|
|
error = lock_page_killable(page);
|
|
if (unlikely(error))
|
|
goto readpage_error;
|
|
if (!PageUptodate(page)) {
|
|
if (page->mapping == NULL) {
|
|
/*
|
|
* invalidate_inode_pages got it
|
|
*/
|
|
unlock_page(page);
|
|
page_cache_release(page);
|
|
goto find_page;
|
|
}
|
|
unlock_page(page);
|
|
shrink_readahead_size_eio(filp, ra);
|
|
error = -EIO;
|
|
goto readpage_error;
|
|
}
|
|
unlock_page(page);
|
|
}
|
|
|
|
goto page_ok;
|
|
|
|
readpage_error:
|
|
/* UHHUH! A synchronous read error occurred. Report it */
|
|
desc->error = error;
|
|
page_cache_release(page);
|
|
goto out;
|
|
|
|
no_cached_page:
|
|
/*
|
|
* Ok, it wasn't cached, so we need to create a new
|
|
* page..
|
|
*/
|
|
page = page_cache_alloc_cold(mapping);
|
|
if (!page) {
|
|
desc->error = -ENOMEM;
|
|
goto out;
|
|
}
|
|
error = add_to_page_cache_lru(page, mapping,
|
|
index, GFP_KERNEL);
|
|
if (error) {
|
|
page_cache_release(page);
|
|
if (error == -EEXIST)
|
|
goto find_page;
|
|
desc->error = error;
|
|
goto out;
|
|
}
|
|
goto readpage;
|
|
}
|
|
|
|
out:
|
|
ra->prev_pos = prev_index;
|
|
ra->prev_pos <<= PAGE_CACHE_SHIFT;
|
|
ra->prev_pos |= prev_offset;
|
|
|
|
*ppos = ((loff_t)index << PAGE_CACHE_SHIFT) + offset;
|
|
file_accessed(filp);
|
|
}
|
|
|
|
int file_read_actor(read_descriptor_t *desc, struct page *page,
|
|
unsigned long offset, unsigned long size)
|
|
{
|
|
char *kaddr;
|
|
unsigned long left, count = desc->count;
|
|
|
|
if (size > count)
|
|
size = count;
|
|
|
|
/*
|
|
* Faults on the destination of a read are common, so do it before
|
|
* taking the kmap.
|
|
*/
|
|
if (!fault_in_pages_writeable(desc->arg.buf, size)) {
|
|
kaddr = kmap_atomic(page, KM_USER0);
|
|
left = __copy_to_user_inatomic(desc->arg.buf,
|
|
kaddr + offset, size);
|
|
kunmap_atomic(kaddr, KM_USER0);
|
|
if (left == 0)
|
|
goto success;
|
|
}
|
|
|
|
/* Do it the slow way */
|
|
kaddr = kmap(page);
|
|
left = __copy_to_user(desc->arg.buf, kaddr + offset, size);
|
|
kunmap(page);
|
|
|
|
if (left) {
|
|
size -= left;
|
|
desc->error = -EFAULT;
|
|
}
|
|
success:
|
|
desc->count = count - size;
|
|
desc->written += size;
|
|
desc->arg.buf += size;
|
|
return size;
|
|
}
|
|
|
|
/*
|
|
* Performs necessary checks before doing a write
|
|
* @iov: io vector request
|
|
* @nr_segs: number of segments in the iovec
|
|
* @count: number of bytes to write
|
|
* @access_flags: type of access: %VERIFY_READ or %VERIFY_WRITE
|
|
*
|
|
* Adjust number of segments and amount of bytes to write (nr_segs should be
|
|
* properly initialized first). Returns appropriate error code that caller
|
|
* should return or zero in case that write should be allowed.
|
|
*/
|
|
int generic_segment_checks(const struct iovec *iov,
|
|
unsigned long *nr_segs, size_t *count, int access_flags)
|
|
{
|
|
unsigned long seg;
|
|
size_t cnt = 0;
|
|
for (seg = 0; seg < *nr_segs; seg++) {
|
|
const struct iovec *iv = &iov[seg];
|
|
|
|
/*
|
|
* If any segment has a negative length, or the cumulative
|
|
* length ever wraps negative then return -EINVAL.
|
|
*/
|
|
cnt += iv->iov_len;
|
|
if (unlikely((ssize_t)(cnt|iv->iov_len) < 0))
|
|
return -EINVAL;
|
|
if (access_ok(access_flags, iv->iov_base, iv->iov_len))
|
|
continue;
|
|
if (seg == 0)
|
|
return -EFAULT;
|
|
*nr_segs = seg;
|
|
cnt -= iv->iov_len; /* This segment is no good */
|
|
break;
|
|
}
|
|
*count = cnt;
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(generic_segment_checks);
|
|
|
|
/**
|
|
* generic_file_aio_read - generic filesystem read routine
|
|
* @iocb: kernel I/O control block
|
|
* @iov: io vector request
|
|
* @nr_segs: number of segments in the iovec
|
|
* @pos: current file position
|
|
*
|
|
* This is the "read()" routine for all filesystems
|
|
* that can use the page cache directly.
|
|
*/
|
|
ssize_t
|
|
generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
|
|
unsigned long nr_segs, loff_t pos)
|
|
{
|
|
struct file *filp = iocb->ki_filp;
|
|
ssize_t retval;
|
|
unsigned long seg;
|
|
size_t count;
|
|
loff_t *ppos = &iocb->ki_pos;
|
|
|
|
count = 0;
|
|
retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE);
|
|
if (retval)
|
|
return retval;
|
|
|
|
/* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
|
|
if (filp->f_flags & O_DIRECT) {
|
|
loff_t size;
|
|
struct address_space *mapping;
|
|
struct inode *inode;
|
|
|
|
mapping = filp->f_mapping;
|
|
inode = mapping->host;
|
|
if (!count)
|
|
goto out; /* skip atime */
|
|
size = i_size_read(inode);
|
|
if (pos < size) {
|
|
retval = filemap_write_and_wait_range(mapping, pos,
|
|
pos + iov_length(iov, nr_segs) - 1);
|
|
if (!retval) {
|
|
retval = mapping->a_ops->direct_IO(READ, iocb,
|
|
iov, pos, nr_segs);
|
|
}
|
|
if (retval > 0)
|
|
*ppos = pos + retval;
|
|
if (retval) {
|
|
file_accessed(filp);
|
|
goto out;
|
|
}
|
|
}
|
|
}
|
|
|
|
for (seg = 0; seg < nr_segs; seg++) {
|
|
read_descriptor_t desc;
|
|
|
|
desc.written = 0;
|
|
desc.arg.buf = iov[seg].iov_base;
|
|
desc.count = iov[seg].iov_len;
|
|
if (desc.count == 0)
|
|
continue;
|
|
desc.error = 0;
|
|
do_generic_file_read(filp, ppos, &desc, file_read_actor);
|
|
retval += desc.written;
|
|
if (desc.error) {
|
|
retval = retval ?: desc.error;
|
|
break;
|
|
}
|
|
if (desc.count > 0)
|
|
break;
|
|
}
|
|
out:
|
|
return retval;
|
|
}
|
|
EXPORT_SYMBOL(generic_file_aio_read);
|
|
|
|
static ssize_t
|
|
do_readahead(struct address_space *mapping, struct file *filp,
|
|
pgoff_t index, unsigned long nr)
|
|
{
|
|
if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage)
|
|
return -EINVAL;
|
|
|
|
force_page_cache_readahead(mapping, filp, index,
|
|
max_sane_readahead(nr));
|
|
return 0;
|
|
}
|
|
|
|
SYSCALL_DEFINE(readahead)(int fd, loff_t offset, size_t count)
|
|
{
|
|
ssize_t ret;
|
|
struct file *file;
|
|
|
|
ret = -EBADF;
|
|
file = fget(fd);
|
|
if (file) {
|
|
if (file->f_mode & FMODE_READ) {
|
|
struct address_space *mapping = file->f_mapping;
|
|
pgoff_t start = offset >> PAGE_CACHE_SHIFT;
|
|
pgoff_t end = (offset + count - 1) >> PAGE_CACHE_SHIFT;
|
|
unsigned long len = end - start + 1;
|
|
ret = do_readahead(mapping, file, start, len);
|
|
}
|
|
fput(file);
|
|
}
|
|
return ret;
|
|
}
|
|
#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
|
|
asmlinkage long SyS_readahead(long fd, loff_t offset, long count)
|
|
{
|
|
return SYSC_readahead((int) fd, offset, (size_t) count);
|
|
}
|
|
SYSCALL_ALIAS(sys_readahead, SyS_readahead);
|
|
#endif
|
|
|
|
#ifdef CONFIG_MMU
|
|
/**
|
|
* page_cache_read - adds requested page to the page cache if not already there
|
|
* @file: file to read
|
|
* @offset: page index
|
|
*
|
|
* This adds the requested page to the page cache if it isn't already there,
|
|
* and schedules an I/O to read in its contents from disk.
|
|
*/
|
|
static int page_cache_read(struct file *file, pgoff_t offset)
|
|
{
|
|
struct address_space *mapping = file->f_mapping;
|
|
struct page *page;
|
|
int ret;
|
|
|
|
do {
|
|
page = page_cache_alloc_cold(mapping);
|
|
if (!page)
|
|
return -ENOMEM;
|
|
|
|
ret = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL);
|
|
if (ret == 0)
|
|
ret = mapping->a_ops->readpage(file, page);
|
|
else if (ret == -EEXIST)
|
|
ret = 0; /* losing race to add is OK */
|
|
|
|
page_cache_release(page);
|
|
|
|
} while (ret == AOP_TRUNCATED_PAGE);
|
|
|
|
return ret;
|
|
}
|
|
|
|
#define MMAP_LOTSAMISS (100)
|
|
|
|
/**
|
|
* filemap_fault - read in file data for page fault handling
|
|
* @vma: vma in which the fault was taken
|
|
* @vmf: struct vm_fault containing details of the fault
|
|
*
|
|
* filemap_fault() is invoked via the vma operations vector for a
|
|
* mapped memory region to read in file data during a page fault.
|
|
*
|
|
* The goto's are kind of ugly, but this streamlines the normal case of having
|
|
* it in the page cache, and handles the special cases reasonably without
|
|
* having a lot of duplicated code.
|
|
*/
|
|
int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
|
|
{
|
|
int error;
|
|
struct file *file = vma->vm_file;
|
|
struct address_space *mapping = file->f_mapping;
|
|
struct file_ra_state *ra = &file->f_ra;
|
|
struct inode *inode = mapping->host;
|
|
struct page *page;
|
|
pgoff_t size;
|
|
int did_readaround = 0;
|
|
int ret = 0;
|
|
|
|
size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
|
|
if (vmf->pgoff >= size)
|
|
return VM_FAULT_SIGBUS;
|
|
|
|
/* If we don't want any read-ahead, don't bother */
|
|
if (VM_RandomReadHint(vma))
|
|
goto no_cached_page;
|
|
|
|
/*
|
|
* Do we have something in the page cache already?
|
|
*/
|
|
retry_find:
|
|
page = find_lock_page(mapping, vmf->pgoff);
|
|
/*
|
|
* For sequential accesses, we use the generic readahead logic.
|
|
*/
|
|
if (VM_SequentialReadHint(vma)) {
|
|
if (!page) {
|
|
page_cache_sync_readahead(mapping, ra, file,
|
|
vmf->pgoff, 1);
|
|
page = find_lock_page(mapping, vmf->pgoff);
|
|
if (!page)
|
|
goto no_cached_page;
|
|
}
|
|
if (PageReadahead(page)) {
|
|
page_cache_async_readahead(mapping, ra, file, page,
|
|
vmf->pgoff, 1);
|
|
}
|
|
}
|
|
|
|
if (!page) {
|
|
unsigned long ra_pages;
|
|
|
|
ra->mmap_miss++;
|
|
|
|
/*
|
|
* Do we miss much more than hit in this file? If so,
|
|
* stop bothering with read-ahead. It will only hurt.
|
|
*/
|
|
if (ra->mmap_miss > MMAP_LOTSAMISS)
|
|
goto no_cached_page;
|
|
|
|
/*
|
|
* To keep the pgmajfault counter straight, we need to
|
|
* check did_readaround, as this is an inner loop.
|
|
*/
|
|
if (!did_readaround) {
|
|
ret = VM_FAULT_MAJOR;
|
|
count_vm_event(PGMAJFAULT);
|
|
}
|
|
did_readaround = 1;
|
|
ra_pages = max_sane_readahead(file->f_ra.ra_pages);
|
|
if (ra_pages) {
|
|
pgoff_t start = 0;
|
|
|
|
if (vmf->pgoff > ra_pages / 2)
|
|
start = vmf->pgoff - ra_pages / 2;
|
|
do_page_cache_readahead(mapping, file, start, ra_pages);
|
|
}
|
|
page = find_lock_page(mapping, vmf->pgoff);
|
|
if (!page)
|
|
goto no_cached_page;
|
|
}
|
|
|
|
if (!did_readaround)
|
|
ra->mmap_miss--;
|
|
|
|
/*
|
|
* We have a locked page in the page cache, now we need to check
|
|
* that it's up-to-date. If not, it is going to be due to an error.
|
|
*/
|
|
if (unlikely(!PageUptodate(page)))
|
|
goto page_not_uptodate;
|
|
|
|
/* Must recheck i_size under page lock */
|
|
size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
|
|
if (unlikely(vmf->pgoff >= size)) {
|
|
unlock_page(page);
|
|
page_cache_release(page);
|
|
return VM_FAULT_SIGBUS;
|
|
}
|
|
|
|
/*
|
|
* Found the page and have a reference on it.
|
|
*/
|
|
ra->prev_pos = (loff_t)page->index << PAGE_CACHE_SHIFT;
|
|
vmf->page = page;
|
|
return ret | VM_FAULT_LOCKED;
|
|
|
|
no_cached_page:
|
|
/*
|
|
* We're only likely to ever get here if MADV_RANDOM is in
|
|
* effect.
|
|
*/
|
|
error = page_cache_read(file, vmf->pgoff);
|
|
|
|
/*
|
|
* The page we want has now been added to the page cache.
|
|
* In the unlikely event that someone removed it in the
|
|
* meantime, we'll just come back here and read it again.
|
|
*/
|
|
if (error >= 0)
|
|
goto retry_find;
|
|
|
|
/*
|
|
* An error return from page_cache_read can result if the
|
|
* system is low on memory, or a problem occurs while trying
|
|
* to schedule I/O.
|
|
*/
|
|
if (error == -ENOMEM)
|
|
return VM_FAULT_OOM;
|
|
return VM_FAULT_SIGBUS;
|
|
|
|
page_not_uptodate:
|
|
/* IO error path */
|
|
if (!did_readaround) {
|
|
ret = VM_FAULT_MAJOR;
|
|
count_vm_event(PGMAJFAULT);
|
|
}
|
|
|
|
/*
|
|
* Umm, take care of errors if the page isn't up-to-date.
|
|
* Try to re-read it _once_. We do this synchronously,
|
|
* because there really aren't any performance issues here
|
|
* and we need to check for errors.
|
|
*/
|
|
ClearPageError(page);
|
|
error = mapping->a_ops->readpage(file, page);
|
|
if (!error) {
|
|
wait_on_page_locked(page);
|
|
if (!PageUptodate(page))
|
|
error = -EIO;
|
|
}
|
|
page_cache_release(page);
|
|
|
|
if (!error || error == AOP_TRUNCATED_PAGE)
|
|
goto retry_find;
|
|
|
|
/* Things didn't work out. Return zero to tell the mm layer so. */
|
|
shrink_readahead_size_eio(file, ra);
|
|
return VM_FAULT_SIGBUS;
|
|
}
|
|
EXPORT_SYMBOL(filemap_fault);
|
|
|
|
struct vm_operations_struct generic_file_vm_ops = {
|
|
.fault = filemap_fault,
|
|
};
|
|
|
|
/* This is used for a general mmap of a disk file */
|
|
|
|
int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
|
|
{
|
|
struct address_space *mapping = file->f_mapping;
|
|
|
|
if (!mapping->a_ops->readpage)
|
|
return -ENOEXEC;
|
|
file_accessed(file);
|
|
vma->vm_ops = &generic_file_vm_ops;
|
|
vma->vm_flags |= VM_CAN_NONLINEAR;
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* This is for filesystems which do not implement ->writepage.
|
|
*/
|
|
int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma)
|
|
{
|
|
if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
|
|
return -EINVAL;
|
|
return generic_file_mmap(file, vma);
|
|
}
|
|
#else
|
|
int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
|
|
{
|
|
return -ENOSYS;
|
|
}
|
|
int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma)
|
|
{
|
|
return -ENOSYS;
|
|
}
|
|
#endif /* CONFIG_MMU */
|
|
|
|
EXPORT_SYMBOL(generic_file_mmap);
|
|
EXPORT_SYMBOL(generic_file_readonly_mmap);
|
|
|
|
static struct page *__read_cache_page(struct address_space *mapping,
|
|
pgoff_t index,
|
|
int (*filler)(void *,struct page*),
|
|
void *data)
|
|
{
|
|
struct page *page;
|
|
int err;
|
|
repeat:
|
|
page = find_get_page(mapping, index);
|
|
if (!page) {
|
|
page = page_cache_alloc_cold(mapping);
|
|
if (!page)
|
|
return ERR_PTR(-ENOMEM);
|
|
err = add_to_page_cache_lru(page, mapping, index, GFP_KERNEL);
|
|
if (unlikely(err)) {
|
|
page_cache_release(page);
|
|
if (err == -EEXIST)
|
|
goto repeat;
|
|
/* Presumably ENOMEM for radix tree node */
|
|
return ERR_PTR(err);
|
|
}
|
|
err = filler(data, page);
|
|
if (err < 0) {
|
|
page_cache_release(page);
|
|
page = ERR_PTR(err);
|
|
}
|
|
}
|
|
return page;
|
|
}
|
|
|
|
/**
|
|
* read_cache_page_async - read into page cache, fill it if needed
|
|
* @mapping: the page's address_space
|
|
* @index: the page index
|
|
* @filler: function to perform the read
|
|
* @data: destination for read data
|
|
*
|
|
* Same as read_cache_page, but don't wait for page to become unlocked
|
|
* after submitting it to the filler.
|
|
*
|
|
* Read into the page cache. If a page already exists, and PageUptodate() is
|
|
* not set, try to fill the page but don't wait for it to become unlocked.
|
|
*
|
|
* If the page does not get brought uptodate, return -EIO.
|
|
*/
|
|
struct page *read_cache_page_async(struct address_space *mapping,
|
|
pgoff_t index,
|
|
int (*filler)(void *,struct page*),
|
|
void *data)
|
|
{
|
|
struct page *page;
|
|
int err;
|
|
|
|
retry:
|
|
page = __read_cache_page(mapping, index, filler, data);
|
|
if (IS_ERR(page))
|
|
return page;
|
|
if (PageUptodate(page))
|
|
goto out;
|
|
|
|
lock_page(page);
|
|
if (!page->mapping) {
|
|
unlock_page(page);
|
|
page_cache_release(page);
|
|
goto retry;
|
|
}
|
|
if (PageUptodate(page)) {
|
|
unlock_page(page);
|
|
goto out;
|
|
}
|
|
err = filler(data, page);
|
|
if (err < 0) {
|
|
page_cache_release(page);
|
|
return ERR_PTR(err);
|
|
}
|
|
out:
|
|
mark_page_accessed(page);
|
|
return page;
|
|
}
|
|
EXPORT_SYMBOL(read_cache_page_async);
|
|
|
|
/**
|
|
* read_cache_page - read into page cache, fill it if needed
|
|
* @mapping: the page's address_space
|
|
* @index: the page index
|
|
* @filler: function to perform the read
|
|
* @data: destination for read data
|
|
*
|
|
* Read into the page cache. If a page already exists, and PageUptodate() is
|
|
* not set, try to fill the page then wait for it to become unlocked.
|
|
*
|
|
* If the page does not get brought uptodate, return -EIO.
|
|
*/
|
|
struct page *read_cache_page(struct address_space *mapping,
|
|
pgoff_t index,
|
|
int (*filler)(void *,struct page*),
|
|
void *data)
|
|
{
|
|
struct page *page;
|
|
|
|
page = read_cache_page_async(mapping, index, filler, data);
|
|
if (IS_ERR(page))
|
|
goto out;
|
|
wait_on_page_locked(page);
|
|
if (!PageUptodate(page)) {
|
|
page_cache_release(page);
|
|
page = ERR_PTR(-EIO);
|
|
}
|
|
out:
|
|
return page;
|
|
}
|
|
EXPORT_SYMBOL(read_cache_page);
|
|
|
|
/*
|
|
* The logic we want is
|
|
*
|
|
* if suid or (sgid and xgrp)
|
|
* remove privs
|
|
*/
|
|
int should_remove_suid(struct dentry *dentry)
|
|
{
|
|
mode_t mode = dentry->d_inode->i_mode;
|
|
int kill = 0;
|
|
|
|
/* suid always must be killed */
|
|
if (unlikely(mode & S_ISUID))
|
|
kill = ATTR_KILL_SUID;
|
|
|
|
/*
|
|
* sgid without any exec bits is just a mandatory locking mark; leave
|
|
* it alone. If some exec bits are set, it's a real sgid; kill it.
|
|
*/
|
|
if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
|
|
kill |= ATTR_KILL_SGID;
|
|
|
|
if (unlikely(kill && !capable(CAP_FSETID) && S_ISREG(mode)))
|
|
return kill;
|
|
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(should_remove_suid);
|
|
|
|
static int __remove_suid(struct dentry *dentry, int kill)
|
|
{
|
|
struct iattr newattrs;
|
|
|
|
newattrs.ia_valid = ATTR_FORCE | kill;
|
|
return notify_change(dentry, &newattrs);
|
|
}
|
|
|
|
int file_remove_suid(struct file *file)
|
|
{
|
|
struct dentry *dentry = file->f_path.dentry;
|
|
int killsuid = should_remove_suid(dentry);
|
|
int killpriv = security_inode_need_killpriv(dentry);
|
|
int error = 0;
|
|
|
|
if (killpriv < 0)
|
|
return killpriv;
|
|
if (killpriv)
|
|
error = security_inode_killpriv(dentry);
|
|
if (!error && killsuid)
|
|
error = __remove_suid(dentry, killsuid);
|
|
|
|
return error;
|
|
}
|
|
EXPORT_SYMBOL(file_remove_suid);
|
|
|
|
static size_t __iovec_copy_from_user_inatomic(char *vaddr,
|
|
const struct iovec *iov, size_t base, size_t bytes)
|
|
{
|
|
size_t copied = 0, left = 0;
|
|
|
|
while (bytes) {
|
|
char __user *buf = iov->iov_base + base;
|
|
int copy = min(bytes, iov->iov_len - base);
|
|
|
|
base = 0;
|
|
left = __copy_from_user_inatomic(vaddr, buf, copy);
|
|
copied += copy;
|
|
bytes -= copy;
|
|
vaddr += copy;
|
|
iov++;
|
|
|
|
if (unlikely(left))
|
|
break;
|
|
}
|
|
return copied - left;
|
|
}
|
|
|
|
/*
|
|
* Copy as much as we can into the page and return the number of bytes which
|
|
* were sucessfully copied. If a fault is encountered then return the number of
|
|
* bytes which were copied.
|
|
*/
|
|
size_t iov_iter_copy_from_user_atomic(struct page *page,
|
|
struct iov_iter *i, unsigned long offset, size_t bytes)
|
|
{
|
|
char *kaddr;
|
|
size_t copied;
|
|
|
|
BUG_ON(!in_atomic());
|
|
kaddr = kmap_atomic(page, KM_USER0);
|
|
if (likely(i->nr_segs == 1)) {
|
|
int left;
|
|
char __user *buf = i->iov->iov_base + i->iov_offset;
|
|
left = __copy_from_user_inatomic(kaddr + offset, buf, bytes);
|
|
copied = bytes - left;
|
|
} else {
|
|
copied = __iovec_copy_from_user_inatomic(kaddr + offset,
|
|
i->iov, i->iov_offset, bytes);
|
|
}
|
|
kunmap_atomic(kaddr, KM_USER0);
|
|
|
|
return copied;
|
|
}
|
|
EXPORT_SYMBOL(iov_iter_copy_from_user_atomic);
|
|
|
|
/*
|
|
* This has the same sideeffects and return value as
|
|
* iov_iter_copy_from_user_atomic().
|
|
* The difference is that it attempts to resolve faults.
|
|
* Page must not be locked.
|
|
*/
|
|
size_t iov_iter_copy_from_user(struct page *page,
|
|
struct iov_iter *i, unsigned long offset, size_t bytes)
|
|
{
|
|
char *kaddr;
|
|
size_t copied;
|
|
|
|
kaddr = kmap(page);
|
|
if (likely(i->nr_segs == 1)) {
|
|
int left;
|
|
char __user *buf = i->iov->iov_base + i->iov_offset;
|
|
left = __copy_from_user(kaddr + offset, buf, bytes);
|
|
copied = bytes - left;
|
|
} else {
|
|
copied = __iovec_copy_from_user_inatomic(kaddr + offset,
|
|
i->iov, i->iov_offset, bytes);
|
|
}
|
|
kunmap(page);
|
|
return copied;
|
|
}
|
|
EXPORT_SYMBOL(iov_iter_copy_from_user);
|
|
|
|
void iov_iter_advance(struct iov_iter *i, size_t bytes)
|
|
{
|
|
BUG_ON(i->count < bytes);
|
|
|
|
if (likely(i->nr_segs == 1)) {
|
|
i->iov_offset += bytes;
|
|
i->count -= bytes;
|
|
} else {
|
|
const struct iovec *iov = i->iov;
|
|
size_t base = i->iov_offset;
|
|
|
|
/*
|
|
* The !iov->iov_len check ensures we skip over unlikely
|
|
* zero-length segments (without overruning the iovec).
|
|
*/
|
|
while (bytes || unlikely(i->count && !iov->iov_len)) {
|
|
int copy;
|
|
|
|
copy = min(bytes, iov->iov_len - base);
|
|
BUG_ON(!i->count || i->count < copy);
|
|
i->count -= copy;
|
|
bytes -= copy;
|
|
base += copy;
|
|
if (iov->iov_len == base) {
|
|
iov++;
|
|
base = 0;
|
|
}
|
|
}
|
|
i->iov = iov;
|
|
i->iov_offset = base;
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(iov_iter_advance);
|
|
|
|
/*
|
|
* Fault in the first iovec of the given iov_iter, to a maximum length
|
|
* of bytes. Returns 0 on success, or non-zero if the memory could not be
|
|
* accessed (ie. because it is an invalid address).
|
|
*
|
|
* writev-intensive code may want this to prefault several iovecs -- that
|
|
* would be possible (callers must not rely on the fact that _only_ the
|
|
* first iovec will be faulted with the current implementation).
|
|
*/
|
|
int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes)
|
|
{
|
|
char __user *buf = i->iov->iov_base + i->iov_offset;
|
|
bytes = min(bytes, i->iov->iov_len - i->iov_offset);
|
|
return fault_in_pages_readable(buf, bytes);
|
|
}
|
|
EXPORT_SYMBOL(iov_iter_fault_in_readable);
|
|
|
|
/*
|
|
* Return the count of just the current iov_iter segment.
|
|
*/
|
|
size_t iov_iter_single_seg_count(struct iov_iter *i)
|
|
{
|
|
const struct iovec *iov = i->iov;
|
|
if (i->nr_segs == 1)
|
|
return i->count;
|
|
else
|
|
return min(i->count, iov->iov_len - i->iov_offset);
|
|
}
|
|
EXPORT_SYMBOL(iov_iter_single_seg_count);
|
|
|
|
/*
|
|
* Performs necessary checks before doing a write
|
|
*
|
|
* Can adjust writing position or amount of bytes to write.
|
|
* Returns appropriate error code that caller should return or
|
|
* zero in case that write should be allowed.
|
|
*/
|
|
inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk)
|
|
{
|
|
struct inode *inode = file->f_mapping->host;
|
|
unsigned long limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
|
|
|
|
if (unlikely(*pos < 0))
|
|
return -EINVAL;
|
|
|
|
if (!isblk) {
|
|
/* FIXME: this is for backwards compatibility with 2.4 */
|
|
if (file->f_flags & O_APPEND)
|
|
*pos = i_size_read(inode);
|
|
|
|
if (limit != RLIM_INFINITY) {
|
|
if (*pos >= limit) {
|
|
send_sig(SIGXFSZ, current, 0);
|
|
return -EFBIG;
|
|
}
|
|
if (*count > limit - (typeof(limit))*pos) {
|
|
*count = limit - (typeof(limit))*pos;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* LFS rule
|
|
*/
|
|
if (unlikely(*pos + *count > MAX_NON_LFS &&
|
|
!(file->f_flags & O_LARGEFILE))) {
|
|
if (*pos >= MAX_NON_LFS) {
|
|
return -EFBIG;
|
|
}
|
|
if (*count > MAX_NON_LFS - (unsigned long)*pos) {
|
|
*count = MAX_NON_LFS - (unsigned long)*pos;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Are we about to exceed the fs block limit ?
|
|
*
|
|
* If we have written data it becomes a short write. If we have
|
|
* exceeded without writing data we send a signal and return EFBIG.
|
|
* Linus frestrict idea will clean these up nicely..
|
|
*/
|
|
if (likely(!isblk)) {
|
|
if (unlikely(*pos >= inode->i_sb->s_maxbytes)) {
|
|
if (*count || *pos > inode->i_sb->s_maxbytes) {
|
|
return -EFBIG;
|
|
}
|
|
/* zero-length writes at ->s_maxbytes are OK */
|
|
}
|
|
|
|
if (unlikely(*pos + *count > inode->i_sb->s_maxbytes))
|
|
*count = inode->i_sb->s_maxbytes - *pos;
|
|
} else {
|
|
#ifdef CONFIG_BLOCK
|
|
loff_t isize;
|
|
if (bdev_read_only(I_BDEV(inode)))
|
|
return -EPERM;
|
|
isize = i_size_read(inode);
|
|
if (*pos >= isize) {
|
|
if (*count || *pos > isize)
|
|
return -ENOSPC;
|
|
}
|
|
|
|
if (*pos + *count > isize)
|
|
*count = isize - *pos;
|
|
#else
|
|
return -EPERM;
|
|
#endif
|
|
}
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(generic_write_checks);
|
|
|
|
int pagecache_write_begin(struct file *file, struct address_space *mapping,
|
|
loff_t pos, unsigned len, unsigned flags,
|
|
struct page **pagep, void **fsdata)
|
|
{
|
|
const struct address_space_operations *aops = mapping->a_ops;
|
|
|
|
return aops->write_begin(file, mapping, pos, len, flags,
|
|
pagep, fsdata);
|
|
}
|
|
EXPORT_SYMBOL(pagecache_write_begin);
|
|
|
|
int pagecache_write_end(struct file *file, struct address_space *mapping,
|
|
loff_t pos, unsigned len, unsigned copied,
|
|
struct page *page, void *fsdata)
|
|
{
|
|
const struct address_space_operations *aops = mapping->a_ops;
|
|
|
|
mark_page_accessed(page);
|
|
return aops->write_end(file, mapping, pos, len, copied, page, fsdata);
|
|
}
|
|
EXPORT_SYMBOL(pagecache_write_end);
|
|
|
|
ssize_t
|
|
generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
|
|
unsigned long *nr_segs, loff_t pos, loff_t *ppos,
|
|
size_t count, size_t ocount)
|
|
{
|
|
struct file *file = iocb->ki_filp;
|
|
struct address_space *mapping = file->f_mapping;
|
|
struct inode *inode = mapping->host;
|
|
ssize_t written;
|
|
size_t write_len;
|
|
pgoff_t end;
|
|
|
|
if (count != ocount)
|
|
*nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count);
|
|
|
|
write_len = iov_length(iov, *nr_segs);
|
|
end = (pos + write_len - 1) >> PAGE_CACHE_SHIFT;
|
|
|
|
written = filemap_write_and_wait_range(mapping, pos, pos + write_len - 1);
|
|
if (written)
|
|
goto out;
|
|
|
|
/*
|
|
* After a write we want buffered reads to be sure to go to disk to get
|
|
* the new data. We invalidate clean cached page from the region we're
|
|
* about to write. We do this *before* the write so that we can return
|
|
* without clobbering -EIOCBQUEUED from ->direct_IO().
|
|
*/
|
|
if (mapping->nrpages) {
|
|
written = invalidate_inode_pages2_range(mapping,
|
|
pos >> PAGE_CACHE_SHIFT, end);
|
|
/*
|
|
* If a page can not be invalidated, return 0 to fall back
|
|
* to buffered write.
|
|
*/
|
|
if (written) {
|
|
if (written == -EBUSY)
|
|
return 0;
|
|
goto out;
|
|
}
|
|
}
|
|
|
|
written = mapping->a_ops->direct_IO(WRITE, iocb, iov, pos, *nr_segs);
|
|
|
|
/*
|
|
* Finally, try again to invalidate clean pages which might have been
|
|
* cached by non-direct readahead, or faulted in by get_user_pages()
|
|
* if the source of the write was an mmap'ed region of the file
|
|
* we're writing. Either one is a pretty crazy thing to do,
|
|
* so we don't support it 100%. If this invalidation
|
|
* fails, tough, the write still worked...
|
|
*/
|
|
if (mapping->nrpages) {
|
|
invalidate_inode_pages2_range(mapping,
|
|
pos >> PAGE_CACHE_SHIFT, end);
|
|
}
|
|
|
|
if (written > 0) {
|
|
loff_t end = pos + written;
|
|
if (end > i_size_read(inode) && !S_ISBLK(inode->i_mode)) {
|
|
i_size_write(inode, end);
|
|
mark_inode_dirty(inode);
|
|
}
|
|
*ppos = end;
|
|
}
|
|
|
|
/*
|
|
* Sync the fs metadata but not the minor inode changes and
|
|
* of course not the data as we did direct DMA for the IO.
|
|
* i_mutex is held, which protects generic_osync_inode() from
|
|
* livelocking. AIO O_DIRECT ops attempt to sync metadata here.
|
|
*/
|
|
out:
|
|
if ((written >= 0 || written == -EIOCBQUEUED) &&
|
|
((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
|
|
int err = generic_osync_inode(inode, mapping, OSYNC_METADATA);
|
|
if (err < 0)
|
|
written = err;
|
|
}
|
|
return written;
|
|
}
|
|
EXPORT_SYMBOL(generic_file_direct_write);
|
|
|
|
/*
|
|
* Find or create a page at the given pagecache position. Return the locked
|
|
* page. This function is specifically for buffered writes.
|
|
*/
|
|
struct page *grab_cache_page_write_begin(struct address_space *mapping,
|
|
pgoff_t index, unsigned flags)
|
|
{
|
|
int status;
|
|
struct page *page;
|
|
gfp_t gfp_notmask = 0;
|
|
if (flags & AOP_FLAG_NOFS)
|
|
gfp_notmask = __GFP_FS;
|
|
repeat:
|
|
page = find_lock_page(mapping, index);
|
|
if (likely(page))
|
|
return page;
|
|
|
|
page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~gfp_notmask);
|
|
if (!page)
|
|
return NULL;
|
|
status = add_to_page_cache_lru(page, mapping, index,
|
|
GFP_KERNEL & ~gfp_notmask);
|
|
if (unlikely(status)) {
|
|
page_cache_release(page);
|
|
if (status == -EEXIST)
|
|
goto repeat;
|
|
return NULL;
|
|
}
|
|
return page;
|
|
}
|
|
EXPORT_SYMBOL(grab_cache_page_write_begin);
|
|
|
|
static ssize_t generic_perform_write(struct file *file,
|
|
struct iov_iter *i, loff_t pos)
|
|
{
|
|
struct address_space *mapping = file->f_mapping;
|
|
const struct address_space_operations *a_ops = mapping->a_ops;
|
|
long status = 0;
|
|
ssize_t written = 0;
|
|
unsigned int flags = 0;
|
|
|
|
/*
|
|
* Copies from kernel address space cannot fail (NFSD is a big user).
|
|
*/
|
|
if (segment_eq(get_fs(), KERNEL_DS))
|
|
flags |= AOP_FLAG_UNINTERRUPTIBLE;
|
|
|
|
do {
|
|
struct page *page;
|
|
pgoff_t index; /* Pagecache index for current page */
|
|
unsigned long offset; /* Offset into pagecache page */
|
|
unsigned long bytes; /* Bytes to write to page */
|
|
size_t copied; /* Bytes copied from user */
|
|
void *fsdata;
|
|
|
|
offset = (pos & (PAGE_CACHE_SIZE - 1));
|
|
index = pos >> PAGE_CACHE_SHIFT;
|
|
bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset,
|
|
iov_iter_count(i));
|
|
|
|
again:
|
|
|
|
/*
|
|
* Bring in the user page that we will copy from _first_.
|
|
* Otherwise there's a nasty deadlock on copying from the
|
|
* same page as we're writing to, without it being marked
|
|
* up-to-date.
|
|
*
|
|
* Not only is this an optimisation, but it is also required
|
|
* to check that the address is actually valid, when atomic
|
|
* usercopies are used, below.
|
|
*/
|
|
if (unlikely(iov_iter_fault_in_readable(i, bytes))) {
|
|
status = -EFAULT;
|
|
break;
|
|
}
|
|
|
|
status = a_ops->write_begin(file, mapping, pos, bytes, flags,
|
|
&page, &fsdata);
|
|
if (unlikely(status))
|
|
break;
|
|
|
|
pagefault_disable();
|
|
copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes);
|
|
pagefault_enable();
|
|
flush_dcache_page(page);
|
|
|
|
status = a_ops->write_end(file, mapping, pos, bytes, copied,
|
|
page, fsdata);
|
|
if (unlikely(status < 0))
|
|
break;
|
|
copied = status;
|
|
|
|
cond_resched();
|
|
|
|
iov_iter_advance(i, copied);
|
|
if (unlikely(copied == 0)) {
|
|
/*
|
|
* If we were unable to copy any data at all, we must
|
|
* fall back to a single segment length write.
|
|
*
|
|
* If we didn't fallback here, we could livelock
|
|
* because not all segments in the iov can be copied at
|
|
* once without a pagefault.
|
|
*/
|
|
bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset,
|
|
iov_iter_single_seg_count(i));
|
|
goto again;
|
|
}
|
|
pos += copied;
|
|
written += copied;
|
|
|
|
balance_dirty_pages_ratelimited(mapping);
|
|
|
|
} while (iov_iter_count(i));
|
|
|
|
return written ? written : status;
|
|
}
|
|
|
|
ssize_t
|
|
generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
|
|
unsigned long nr_segs, loff_t pos, loff_t *ppos,
|
|
size_t count, ssize_t written)
|
|
{
|
|
struct file *file = iocb->ki_filp;
|
|
struct address_space *mapping = file->f_mapping;
|
|
const struct address_space_operations *a_ops = mapping->a_ops;
|
|
struct inode *inode = mapping->host;
|
|
ssize_t status;
|
|
struct iov_iter i;
|
|
|
|
iov_iter_init(&i, iov, nr_segs, count, written);
|
|
status = generic_perform_write(file, &i, pos);
|
|
|
|
if (likely(status >= 0)) {
|
|
written += status;
|
|
*ppos = pos + status;
|
|
|
|
/*
|
|
* For now, when the user asks for O_SYNC, we'll actually give
|
|
* O_DSYNC
|
|
*/
|
|
if (unlikely((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
|
|
if (!a_ops->writepage || !is_sync_kiocb(iocb))
|
|
status = generic_osync_inode(inode, mapping,
|
|
OSYNC_METADATA|OSYNC_DATA);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* If we get here for O_DIRECT writes then we must have fallen through
|
|
* to buffered writes (block instantiation inside i_size). So we sync
|
|
* the file data here, to try to honour O_DIRECT expectations.
|
|
*/
|
|
if (unlikely(file->f_flags & O_DIRECT) && written)
|
|
status = filemap_write_and_wait_range(mapping,
|
|
pos, pos + written - 1);
|
|
|
|
return written ? written : status;
|
|
}
|
|
EXPORT_SYMBOL(generic_file_buffered_write);
|
|
|
|
static ssize_t
|
|
__generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
|
|
unsigned long nr_segs, loff_t *ppos)
|
|
{
|
|
struct file *file = iocb->ki_filp;
|
|
struct address_space * mapping = file->f_mapping;
|
|
size_t ocount; /* original count */
|
|
size_t count; /* after file limit checks */
|
|
struct inode *inode = mapping->host;
|
|
loff_t pos;
|
|
ssize_t written;
|
|
ssize_t err;
|
|
|
|
ocount = 0;
|
|
err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ);
|
|
if (err)
|
|
return err;
|
|
|
|
count = ocount;
|
|
pos = *ppos;
|
|
|
|
vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
|
|
|
|
/* We can write back this queue in page reclaim */
|
|
current->backing_dev_info = mapping->backing_dev_info;
|
|
written = 0;
|
|
|
|
err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
|
|
if (err)
|
|
goto out;
|
|
|
|
if (count == 0)
|
|
goto out;
|
|
|
|
err = file_remove_suid(file);
|
|
if (err)
|
|
goto out;
|
|
|
|
file_update_time(file);
|
|
|
|
/* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
|
|
if (unlikely(file->f_flags & O_DIRECT)) {
|
|
loff_t endbyte;
|
|
ssize_t written_buffered;
|
|
|
|
written = generic_file_direct_write(iocb, iov, &nr_segs, pos,
|
|
ppos, count, ocount);
|
|
if (written < 0 || written == count)
|
|
goto out;
|
|
/*
|
|
* direct-io write to a hole: fall through to buffered I/O
|
|
* for completing the rest of the request.
|
|
*/
|
|
pos += written;
|
|
count -= written;
|
|
written_buffered = generic_file_buffered_write(iocb, iov,
|
|
nr_segs, pos, ppos, count,
|
|
written);
|
|
/*
|
|
* If generic_file_buffered_write() retuned a synchronous error
|
|
* then we want to return the number of bytes which were
|
|
* direct-written, or the error code if that was zero. Note
|
|
* that this differs from normal direct-io semantics, which
|
|
* will return -EFOO even if some bytes were written.
|
|
*/
|
|
if (written_buffered < 0) {
|
|
err = written_buffered;
|
|
goto out;
|
|
}
|
|
|
|
/*
|
|
* We need to ensure that the page cache pages are written to
|
|
* disk and invalidated to preserve the expected O_DIRECT
|
|
* semantics.
|
|
*/
|
|
endbyte = pos + written_buffered - written - 1;
|
|
err = do_sync_mapping_range(file->f_mapping, pos, endbyte,
|
|
SYNC_FILE_RANGE_WAIT_BEFORE|
|
|
SYNC_FILE_RANGE_WRITE|
|
|
SYNC_FILE_RANGE_WAIT_AFTER);
|
|
if (err == 0) {
|
|
written = written_buffered;
|
|
invalidate_mapping_pages(mapping,
|
|
pos >> PAGE_CACHE_SHIFT,
|
|
endbyte >> PAGE_CACHE_SHIFT);
|
|
} else {
|
|
/*
|
|
* We don't know how much we wrote, so just return
|
|
* the number of bytes which were direct-written
|
|
*/
|
|
}
|
|
} else {
|
|
written = generic_file_buffered_write(iocb, iov, nr_segs,
|
|
pos, ppos, count, written);
|
|
}
|
|
out:
|
|
current->backing_dev_info = NULL;
|
|
return written ? written : err;
|
|
}
|
|
|
|
ssize_t generic_file_aio_write_nolock(struct kiocb *iocb,
|
|
const struct iovec *iov, unsigned long nr_segs, loff_t pos)
|
|
{
|
|
struct file *file = iocb->ki_filp;
|
|
struct address_space *mapping = file->f_mapping;
|
|
struct inode *inode = mapping->host;
|
|
ssize_t ret;
|
|
|
|
BUG_ON(iocb->ki_pos != pos);
|
|
|
|
ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs,
|
|
&iocb->ki_pos);
|
|
|
|
if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
|
|
ssize_t err;
|
|
|
|
err = sync_page_range_nolock(inode, mapping, pos, ret);
|
|
if (err < 0)
|
|
ret = err;
|
|
}
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(generic_file_aio_write_nolock);
|
|
|
|
ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
|
|
unsigned long nr_segs, loff_t pos)
|
|
{
|
|
struct file *file = iocb->ki_filp;
|
|
struct address_space *mapping = file->f_mapping;
|
|
struct inode *inode = mapping->host;
|
|
ssize_t ret;
|
|
|
|
BUG_ON(iocb->ki_pos != pos);
|
|
|
|
mutex_lock(&inode->i_mutex);
|
|
ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs,
|
|
&iocb->ki_pos);
|
|
mutex_unlock(&inode->i_mutex);
|
|
|
|
if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
|
|
ssize_t err;
|
|
|
|
err = sync_page_range(inode, mapping, pos, ret);
|
|
if (err < 0)
|
|
ret = err;
|
|
}
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(generic_file_aio_write);
|
|
|
|
/**
|
|
* try_to_release_page() - release old fs-specific metadata on a page
|
|
*
|
|
* @page: the page which the kernel is trying to free
|
|
* @gfp_mask: memory allocation flags (and I/O mode)
|
|
*
|
|
* The address_space is to try to release any data against the page
|
|
* (presumably at page->private). If the release was successful, return `1'.
|
|
* Otherwise return zero.
|
|
*
|
|
* This may also be called if PG_fscache is set on a page, indicating that the
|
|
* page is known to the local caching routines.
|
|
*
|
|
* The @gfp_mask argument specifies whether I/O may be performed to release
|
|
* this page (__GFP_IO), and whether the call may block (__GFP_WAIT & __GFP_FS).
|
|
*
|
|
*/
|
|
int try_to_release_page(struct page *page, gfp_t gfp_mask)
|
|
{
|
|
struct address_space * const mapping = page->mapping;
|
|
|
|
BUG_ON(!PageLocked(page));
|
|
if (PageWriteback(page))
|
|
return 0;
|
|
|
|
if (mapping && mapping->a_ops->releasepage)
|
|
return mapping->a_ops->releasepage(page, gfp_mask);
|
|
return try_to_free_buffers(page);
|
|
}
|
|
|
|
EXPORT_SYMBOL(try_to_release_page);
|