linux/fs/nilfs2/page.c
Christoph Hellwig 66dabbb65d mm: return an ERR_PTR from __filemap_get_folio
Instead of returning NULL for all errors, distinguish between:

 - no entry found and not asked to allocated (-ENOENT)
 - failed to allocate memory (-ENOMEM)
 - would block (-EAGAIN)

so that callers don't have to guess the error based on the passed in
flags.

Also pass through the error through the direct callers: filemap_get_folio,
filemap_lock_folio filemap_grab_folio and filemap_get_incore_folio.

[hch@lst.de: fix null-pointer deref]
  Link: https://lkml.kernel.org/r/20230310070023.GA13563@lst.de
  Link: https://lkml.kernel.org/r/20230310043137.GA1624890@u2004
Link: https://lkml.kernel.org/r/20230307143410.28031-8-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Ryusuke Konishi <konishi.ryusuke@gmail.com> [nilfs2]
Cc: Andreas Gruenbacher <agruenba@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-04-05 19:42:42 -07:00

542 lines
13 KiB
C

// SPDX-License-Identifier: GPL-2.0+
/*
* Buffer/page management specific to NILFS
*
* Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
*
* Written by Ryusuke Konishi and Seiji Kihara.
*/
#include <linux/pagemap.h>
#include <linux/writeback.h>
#include <linux/swap.h>
#include <linux/bitops.h>
#include <linux/page-flags.h>
#include <linux/list.h>
#include <linux/highmem.h>
#include <linux/pagevec.h>
#include <linux/gfp.h>
#include "nilfs.h"
#include "page.h"
#include "mdt.h"
#define NILFS_BUFFER_INHERENT_BITS \
(BIT(BH_Uptodate) | BIT(BH_Mapped) | BIT(BH_NILFS_Node) | \
BIT(BH_NILFS_Volatile) | BIT(BH_NILFS_Checked))
static struct buffer_head *
__nilfs_get_page_block(struct page *page, unsigned long block, pgoff_t index,
int blkbits, unsigned long b_state)
{
unsigned long first_block;
struct buffer_head *bh;
if (!page_has_buffers(page))
create_empty_buffers(page, 1 << blkbits, b_state);
first_block = (unsigned long)index << (PAGE_SHIFT - blkbits);
bh = nilfs_page_get_nth_block(page, block - first_block);
touch_buffer(bh);
wait_on_buffer(bh);
return bh;
}
struct buffer_head *nilfs_grab_buffer(struct inode *inode,
struct address_space *mapping,
unsigned long blkoff,
unsigned long b_state)
{
int blkbits = inode->i_blkbits;
pgoff_t index = blkoff >> (PAGE_SHIFT - blkbits);
struct page *page;
struct buffer_head *bh;
page = grab_cache_page(mapping, index);
if (unlikely(!page))
return NULL;
bh = __nilfs_get_page_block(page, blkoff, index, blkbits, b_state);
if (unlikely(!bh)) {
unlock_page(page);
put_page(page);
return NULL;
}
return bh;
}
/**
* nilfs_forget_buffer - discard dirty state
* @bh: buffer head of the buffer to be discarded
*/
void nilfs_forget_buffer(struct buffer_head *bh)
{
struct page *page = bh->b_page;
const unsigned long clear_bits =
(BIT(BH_Uptodate) | BIT(BH_Dirty) | BIT(BH_Mapped) |
BIT(BH_Async_Write) | BIT(BH_NILFS_Volatile) |
BIT(BH_NILFS_Checked) | BIT(BH_NILFS_Redirected));
lock_buffer(bh);
set_mask_bits(&bh->b_state, clear_bits, 0);
if (nilfs_page_buffers_clean(page))
__nilfs_clear_page_dirty(page);
bh->b_blocknr = -1;
ClearPageUptodate(page);
ClearPageMappedToDisk(page);
unlock_buffer(bh);
brelse(bh);
}
/**
* nilfs_copy_buffer -- copy buffer data and flags
* @dbh: destination buffer
* @sbh: source buffer
*/
void nilfs_copy_buffer(struct buffer_head *dbh, struct buffer_head *sbh)
{
void *kaddr0, *kaddr1;
unsigned long bits;
struct page *spage = sbh->b_page, *dpage = dbh->b_page;
struct buffer_head *bh;
kaddr0 = kmap_atomic(spage);
kaddr1 = kmap_atomic(dpage);
memcpy(kaddr1 + bh_offset(dbh), kaddr0 + bh_offset(sbh), sbh->b_size);
kunmap_atomic(kaddr1);
kunmap_atomic(kaddr0);
dbh->b_state = sbh->b_state & NILFS_BUFFER_INHERENT_BITS;
dbh->b_blocknr = sbh->b_blocknr;
dbh->b_bdev = sbh->b_bdev;
bh = dbh;
bits = sbh->b_state & (BIT(BH_Uptodate) | BIT(BH_Mapped));
while ((bh = bh->b_this_page) != dbh) {
lock_buffer(bh);
bits &= bh->b_state;
unlock_buffer(bh);
}
if (bits & BIT(BH_Uptodate))
SetPageUptodate(dpage);
else
ClearPageUptodate(dpage);
if (bits & BIT(BH_Mapped))
SetPageMappedToDisk(dpage);
else
ClearPageMappedToDisk(dpage);
}
/**
* nilfs_page_buffers_clean - check if a page has dirty buffers or not.
* @page: page to be checked
*
* nilfs_page_buffers_clean() returns zero if the page has dirty buffers.
* Otherwise, it returns non-zero value.
*/
int nilfs_page_buffers_clean(struct page *page)
{
struct buffer_head *bh, *head;
bh = head = page_buffers(page);
do {
if (buffer_dirty(bh))
return 0;
bh = bh->b_this_page;
} while (bh != head);
return 1;
}
void nilfs_page_bug(struct page *page)
{
struct address_space *m;
unsigned long ino;
if (unlikely(!page)) {
printk(KERN_CRIT "NILFS_PAGE_BUG(NULL)\n");
return;
}
m = page->mapping;
ino = m ? m->host->i_ino : 0;
printk(KERN_CRIT "NILFS_PAGE_BUG(%p): cnt=%d index#=%llu flags=0x%lx "
"mapping=%p ino=%lu\n",
page, page_ref_count(page),
(unsigned long long)page->index, page->flags, m, ino);
if (page_has_buffers(page)) {
struct buffer_head *bh, *head;
int i = 0;
bh = head = page_buffers(page);
do {
printk(KERN_CRIT
" BH[%d] %p: cnt=%d block#=%llu state=0x%lx\n",
i++, bh, atomic_read(&bh->b_count),
(unsigned long long)bh->b_blocknr, bh->b_state);
bh = bh->b_this_page;
} while (bh != head);
}
}
/**
* nilfs_copy_page -- copy the page with buffers
* @dst: destination page
* @src: source page
* @copy_dirty: flag whether to copy dirty states on the page's buffer heads.
*
* This function is for both data pages and btnode pages. The dirty flag
* should be treated by caller. The page must not be under i/o.
* Both src and dst page must be locked
*/
static void nilfs_copy_page(struct page *dst, struct page *src, int copy_dirty)
{
struct buffer_head *dbh, *dbufs, *sbh;
unsigned long mask = NILFS_BUFFER_INHERENT_BITS;
BUG_ON(PageWriteback(dst));
sbh = page_buffers(src);
if (!page_has_buffers(dst))
create_empty_buffers(dst, sbh->b_size, 0);
if (copy_dirty)
mask |= BIT(BH_Dirty);
dbh = dbufs = page_buffers(dst);
do {
lock_buffer(sbh);
lock_buffer(dbh);
dbh->b_state = sbh->b_state & mask;
dbh->b_blocknr = sbh->b_blocknr;
dbh->b_bdev = sbh->b_bdev;
sbh = sbh->b_this_page;
dbh = dbh->b_this_page;
} while (dbh != dbufs);
copy_highpage(dst, src);
if (PageUptodate(src) && !PageUptodate(dst))
SetPageUptodate(dst);
else if (!PageUptodate(src) && PageUptodate(dst))
ClearPageUptodate(dst);
if (PageMappedToDisk(src) && !PageMappedToDisk(dst))
SetPageMappedToDisk(dst);
else if (!PageMappedToDisk(src) && PageMappedToDisk(dst))
ClearPageMappedToDisk(dst);
do {
unlock_buffer(sbh);
unlock_buffer(dbh);
sbh = sbh->b_this_page;
dbh = dbh->b_this_page;
} while (dbh != dbufs);
}
int nilfs_copy_dirty_pages(struct address_space *dmap,
struct address_space *smap)
{
struct folio_batch fbatch;
unsigned int i;
pgoff_t index = 0;
int err = 0;
folio_batch_init(&fbatch);
repeat:
if (!filemap_get_folios_tag(smap, &index, (pgoff_t)-1,
PAGECACHE_TAG_DIRTY, &fbatch))
return 0;
for (i = 0; i < folio_batch_count(&fbatch); i++) {
struct folio *folio = fbatch.folios[i], *dfolio;
folio_lock(folio);
if (unlikely(!folio_test_dirty(folio)))
NILFS_PAGE_BUG(&folio->page, "inconsistent dirty state");
dfolio = filemap_grab_folio(dmap, folio->index);
if (unlikely(IS_ERR(dfolio))) {
/* No empty page is added to the page cache */
folio_unlock(folio);
err = PTR_ERR(dfolio);
break;
}
if (unlikely(!folio_buffers(folio)))
NILFS_PAGE_BUG(&folio->page,
"found empty page in dat page cache");
nilfs_copy_page(&dfolio->page, &folio->page, 1);
filemap_dirty_folio(folio_mapping(dfolio), dfolio);
folio_unlock(dfolio);
folio_put(dfolio);
folio_unlock(folio);
}
folio_batch_release(&fbatch);
cond_resched();
if (likely(!err))
goto repeat;
return err;
}
/**
* nilfs_copy_back_pages -- copy back pages to original cache from shadow cache
* @dmap: destination page cache
* @smap: source page cache
*
* No pages must be added to the cache during this process.
* This must be ensured by the caller.
*/
void nilfs_copy_back_pages(struct address_space *dmap,
struct address_space *smap)
{
struct folio_batch fbatch;
unsigned int i, n;
pgoff_t start = 0;
folio_batch_init(&fbatch);
repeat:
n = filemap_get_folios(smap, &start, ~0UL, &fbatch);
if (!n)
return;
for (i = 0; i < folio_batch_count(&fbatch); i++) {
struct folio *folio = fbatch.folios[i], *dfolio;
pgoff_t index = folio->index;
folio_lock(folio);
dfolio = filemap_lock_folio(dmap, index);
if (!IS_ERR(dfolio)) {
/* overwrite existing folio in the destination cache */
WARN_ON(folio_test_dirty(dfolio));
nilfs_copy_page(&dfolio->page, &folio->page, 0);
folio_unlock(dfolio);
folio_put(dfolio);
/* Do we not need to remove folio from smap here? */
} else {
struct folio *f;
/* move the folio to the destination cache */
xa_lock_irq(&smap->i_pages);
f = __xa_erase(&smap->i_pages, index);
WARN_ON(folio != f);
smap->nrpages--;
xa_unlock_irq(&smap->i_pages);
xa_lock_irq(&dmap->i_pages);
f = __xa_store(&dmap->i_pages, index, folio, GFP_NOFS);
if (unlikely(f)) {
/* Probably -ENOMEM */
folio->mapping = NULL;
folio_put(folio);
} else {
folio->mapping = dmap;
dmap->nrpages++;
if (folio_test_dirty(folio))
__xa_set_mark(&dmap->i_pages, index,
PAGECACHE_TAG_DIRTY);
}
xa_unlock_irq(&dmap->i_pages);
}
folio_unlock(folio);
}
folio_batch_release(&fbatch);
cond_resched();
goto repeat;
}
/**
* nilfs_clear_dirty_pages - discard dirty pages in address space
* @mapping: address space with dirty pages for discarding
* @silent: suppress [true] or print [false] warning messages
*/
void nilfs_clear_dirty_pages(struct address_space *mapping, bool silent)
{
struct folio_batch fbatch;
unsigned int i;
pgoff_t index = 0;
folio_batch_init(&fbatch);
while (filemap_get_folios_tag(mapping, &index, (pgoff_t)-1,
PAGECACHE_TAG_DIRTY, &fbatch)) {
for (i = 0; i < folio_batch_count(&fbatch); i++) {
struct folio *folio = fbatch.folios[i];
folio_lock(folio);
nilfs_clear_dirty_page(&folio->page, silent);
folio_unlock(folio);
}
folio_batch_release(&fbatch);
cond_resched();
}
}
/**
* nilfs_clear_dirty_page - discard dirty page
* @page: dirty page that will be discarded
* @silent: suppress [true] or print [false] warning messages
*/
void nilfs_clear_dirty_page(struct page *page, bool silent)
{
struct inode *inode = page->mapping->host;
struct super_block *sb = inode->i_sb;
BUG_ON(!PageLocked(page));
if (!silent)
nilfs_warn(sb, "discard dirty page: offset=%lld, ino=%lu",
page_offset(page), inode->i_ino);
ClearPageUptodate(page);
ClearPageMappedToDisk(page);
if (page_has_buffers(page)) {
struct buffer_head *bh, *head;
const unsigned long clear_bits =
(BIT(BH_Uptodate) | BIT(BH_Dirty) | BIT(BH_Mapped) |
BIT(BH_Async_Write) | BIT(BH_NILFS_Volatile) |
BIT(BH_NILFS_Checked) | BIT(BH_NILFS_Redirected));
bh = head = page_buffers(page);
do {
lock_buffer(bh);
if (!silent)
nilfs_warn(sb,
"discard dirty block: blocknr=%llu, size=%zu",
(u64)bh->b_blocknr, bh->b_size);
set_mask_bits(&bh->b_state, clear_bits, 0);
unlock_buffer(bh);
} while (bh = bh->b_this_page, bh != head);
}
__nilfs_clear_page_dirty(page);
}
unsigned int nilfs_page_count_clean_buffers(struct page *page,
unsigned int from, unsigned int to)
{
unsigned int block_start, block_end;
struct buffer_head *bh, *head;
unsigned int nc = 0;
for (bh = head = page_buffers(page), block_start = 0;
bh != head || !block_start;
block_start = block_end, bh = bh->b_this_page) {
block_end = block_start + bh->b_size;
if (block_end > from && block_start < to && !buffer_dirty(bh))
nc++;
}
return nc;
}
/*
* NILFS2 needs clear_page_dirty() in the following two cases:
*
* 1) For B-tree node pages and data pages of DAT file, NILFS2 clears dirty
* flag of pages when it copies back pages from shadow cache to the
* original cache.
*
* 2) Some B-tree operations like insertion or deletion may dispose buffers
* in dirty state, and this needs to cancel the dirty state of their pages.
*/
int __nilfs_clear_page_dirty(struct page *page)
{
struct address_space *mapping = page->mapping;
if (mapping) {
xa_lock_irq(&mapping->i_pages);
if (test_bit(PG_dirty, &page->flags)) {
__xa_clear_mark(&mapping->i_pages, page_index(page),
PAGECACHE_TAG_DIRTY);
xa_unlock_irq(&mapping->i_pages);
return clear_page_dirty_for_io(page);
}
xa_unlock_irq(&mapping->i_pages);
return 0;
}
return TestClearPageDirty(page);
}
/**
* nilfs_find_uncommitted_extent - find extent of uncommitted data
* @inode: inode
* @start_blk: start block offset (in)
* @blkoff: start offset of the found extent (out)
*
* This function searches an extent of buffers marked "delayed" which
* starts from a block offset equal to or larger than @start_blk. If
* such an extent was found, this will store the start offset in
* @blkoff and return its length in blocks. Otherwise, zero is
* returned.
*/
unsigned long nilfs_find_uncommitted_extent(struct inode *inode,
sector_t start_blk,
sector_t *blkoff)
{
unsigned int i, nr_folios;
pgoff_t index;
unsigned long length = 0;
struct folio_batch fbatch;
struct folio *folio;
if (inode->i_mapping->nrpages == 0)
return 0;
index = start_blk >> (PAGE_SHIFT - inode->i_blkbits);
folio_batch_init(&fbatch);
repeat:
nr_folios = filemap_get_folios_contig(inode->i_mapping, &index, ULONG_MAX,
&fbatch);
if (nr_folios == 0)
return length;
i = 0;
do {
folio = fbatch.folios[i];
folio_lock(folio);
if (folio_buffers(folio)) {
struct buffer_head *bh, *head;
sector_t b;
b = folio->index << (PAGE_SHIFT - inode->i_blkbits);
bh = head = folio_buffers(folio);
do {
if (b < start_blk)
continue;
if (buffer_delay(bh)) {
if (length == 0)
*blkoff = b;
length++;
} else if (length > 0) {
goto out_locked;
}
} while (++b, bh = bh->b_this_page, bh != head);
} else {
if (length > 0)
goto out_locked;
}
folio_unlock(folio);
} while (++i < nr_folios);
folio_batch_release(&fbatch);
cond_resched();
goto repeat;
out_locked:
folio_unlock(folio);
folio_batch_release(&fbatch);
return length;
}