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a7e3b975a0
Currently when there are buffered writes that were not yet flushed and they fall within allocated ranges of the file (that is, not in holes or beyond eof assuming there are no prealloc extents beyond eof), btrfs simply reports an incorrect number of used blocks through the stat(2) system call (or any of its variants), regardless of mount options or inode flags (compress, compress-force, nodatacow). This is because the number of blocks used that is reported is based on the current number of bytes in the vfs inode plus the number of dealloc bytes in the btrfs inode. The later covers bytes that both fall within allocated regions of the file and holes. Example scenarios where the number of reported blocks is wrong while the buffered writes are not flushed: $ mkfs.btrfs -f /dev/sdc $ mount /dev/sdc /mnt/sdc $ xfs_io -f -c "pwrite -S 0xaa 0 64K" /mnt/sdc/foo1 wrote 65536/65536 bytes at offset 0 64 KiB, 16 ops; 0.0000 sec (259.336 MiB/sec and 66390.0415 ops/sec) $ sync $ xfs_io -c "pwrite -S 0xbb 0 64K" /mnt/sdc/foo1 wrote 65536/65536 bytes at offset 0 64 KiB, 16 ops; 0.0000 sec (192.308 MiB/sec and 49230.7692 ops/sec) # The following should have reported 64K... $ du -h /mnt/sdc/foo1 128K /mnt/sdc/foo1 $ sync # After flushing the buffered write, it now reports the correct value. $ du -h /mnt/sdc/foo1 64K /mnt/sdc/foo1 $ xfs_io -f -c "falloc -k 0 128K" -c "pwrite -S 0xaa 0 64K" /mnt/sdc/foo2 wrote 65536/65536 bytes at offset 0 64 KiB, 16 ops; 0.0000 sec (520.833 MiB/sec and 133333.3333 ops/sec) $ sync $ xfs_io -c "pwrite -S 0xbb 64K 64K" /mnt/sdc/foo2 wrote 65536/65536 bytes at offset 65536 64 KiB, 16 ops; 0.0000 sec (260.417 MiB/sec and 66666.6667 ops/sec) # The following should have reported 128K... $ du -h /mnt/sdc/foo2 192K /mnt/sdc/foo2 $ sync # After flushing the buffered write, it now reports the correct value. $ du -h /mnt/sdc/foo2 128K /mnt/sdc/foo2 So the number of used file blocks is simply incorrect, unlike in other filesystems such as ext4 and xfs for example, but only while the buffered writes are not flushed. Fix this by tracking the number of delalloc bytes that fall within holes and beyond eof of a file, and use instead this new counter when reporting the number of used blocks for an inode. Another different problem that exists is that the delalloc bytes counter is reset when writeback starts (by clearing the EXTENT_DEALLOC flag from the respective range in the inode's iotree) and the vfs inode's bytes counter is only incremented when writeback finishes (through insert_reserved_file_extent()). Therefore while writeback is ongoing we simply report a wrong number of blocks used by an inode if the write operation covers a range previously unallocated. While this change does not fix this problem, it does minimizes it a lot by shortening that time window, as the new dealloc bytes counter (new_delalloc_bytes) is only decremented when writeback finishes right before updating the vfs inode's bytes counter. Fully fixing this second problem is not trivial and will be addressed later by a different patch. Signed-off-by: Filipe Manana <fdmanana@suse.com>
354 lines
9.6 KiB
C
354 lines
9.6 KiB
C
/*
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* Copyright (C) 2007 Oracle. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public
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* License v2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public
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* License along with this program; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 021110-1307, USA.
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*/
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#ifndef __BTRFS_I__
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#define __BTRFS_I__
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#include <linux/hash.h>
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#include "extent_map.h"
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#include "extent_io.h"
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#include "ordered-data.h"
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#include "delayed-inode.h"
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/*
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* ordered_data_close is set by truncate when a file that used
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* to have good data has been truncated to zero. When it is set
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* the btrfs file release call will add this inode to the
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* ordered operations list so that we make sure to flush out any
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* new data the application may have written before commit.
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*/
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#define BTRFS_INODE_ORDERED_DATA_CLOSE 0
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#define BTRFS_INODE_ORPHAN_META_RESERVED 1
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#define BTRFS_INODE_DUMMY 2
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#define BTRFS_INODE_IN_DEFRAG 3
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#define BTRFS_INODE_DELALLOC_META_RESERVED 4
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#define BTRFS_INODE_HAS_ORPHAN_ITEM 5
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#define BTRFS_INODE_HAS_ASYNC_EXTENT 6
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#define BTRFS_INODE_NEEDS_FULL_SYNC 7
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#define BTRFS_INODE_COPY_EVERYTHING 8
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#define BTRFS_INODE_IN_DELALLOC_LIST 9
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#define BTRFS_INODE_READDIO_NEED_LOCK 10
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#define BTRFS_INODE_HAS_PROPS 11
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/* in memory btrfs inode */
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struct btrfs_inode {
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/* which subvolume this inode belongs to */
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struct btrfs_root *root;
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/* key used to find this inode on disk. This is used by the code
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* to read in roots of subvolumes
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*/
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struct btrfs_key location;
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/*
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* Lock for counters and all fields used to determine if the inode is in
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* the log or not (last_trans, last_sub_trans, last_log_commit,
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* logged_trans).
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*/
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spinlock_t lock;
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/* the extent_tree has caches of all the extent mappings to disk */
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struct extent_map_tree extent_tree;
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/* the io_tree does range state (DIRTY, LOCKED etc) */
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struct extent_io_tree io_tree;
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/* special utility tree used to record which mirrors have already been
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* tried when checksums fail for a given block
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*/
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struct extent_io_tree io_failure_tree;
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/* held while logging the inode in tree-log.c */
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struct mutex log_mutex;
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/* held while doing delalloc reservations */
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struct mutex delalloc_mutex;
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/* used to order data wrt metadata */
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struct btrfs_ordered_inode_tree ordered_tree;
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/* list of all the delalloc inodes in the FS. There are times we need
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* to write all the delalloc pages to disk, and this list is used
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* to walk them all.
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*/
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struct list_head delalloc_inodes;
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/* node for the red-black tree that links inodes in subvolume root */
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struct rb_node rb_node;
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unsigned long runtime_flags;
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/* Keep track of who's O_SYNC/fsyncing currently */
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atomic_t sync_writers;
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/* full 64 bit generation number, struct vfs_inode doesn't have a big
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* enough field for this.
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*/
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u64 generation;
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/*
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* transid of the trans_handle that last modified this inode
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*/
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u64 last_trans;
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/*
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* transid that last logged this inode
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*/
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u64 logged_trans;
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/*
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* log transid when this inode was last modified
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*/
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int last_sub_trans;
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/* a local copy of root's last_log_commit */
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int last_log_commit;
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/* total number of bytes pending delalloc, used by stat to calc the
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* real block usage of the file
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*/
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u64 delalloc_bytes;
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/*
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* Total number of bytes pending delalloc that fall within a file
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* range that is either a hole or beyond EOF (and no prealloc extent
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* exists in the range). This is always <= delalloc_bytes.
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*/
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u64 new_delalloc_bytes;
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/*
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* total number of bytes pending defrag, used by stat to check whether
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* it needs COW.
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*/
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u64 defrag_bytes;
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/*
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* the size of the file stored in the metadata on disk. data=ordered
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* means the in-memory i_size might be larger than the size on disk
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* because not all the blocks are written yet.
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*/
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u64 disk_i_size;
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/*
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* if this is a directory then index_cnt is the counter for the index
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* number for new files that are created
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*/
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u64 index_cnt;
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/* Cache the directory index number to speed the dir/file remove */
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u64 dir_index;
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/* the fsync log has some corner cases that mean we have to check
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* directories to see if any unlinks have been done before
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* the directory was logged. See tree-log.c for all the
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* details
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*/
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u64 last_unlink_trans;
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/*
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* Number of bytes outstanding that are going to need csums. This is
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* used in ENOSPC accounting.
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*/
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u64 csum_bytes;
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/* flags field from the on disk inode */
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u32 flags;
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/*
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* Counters to keep track of the number of extent item's we may use due
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* to delalloc and such. outstanding_extents is the number of extent
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* items we think we'll end up using, and reserved_extents is the number
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* of extent items we've reserved metadata for.
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*/
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unsigned outstanding_extents;
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unsigned reserved_extents;
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/*
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* always compress this one file
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*/
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unsigned force_compress;
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struct btrfs_delayed_node *delayed_node;
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/* File creation time. */
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struct timespec i_otime;
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/* Hook into fs_info->delayed_iputs */
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struct list_head delayed_iput;
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long delayed_iput_count;
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/*
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* To avoid races between lockless (i_mutex not held) direct IO writes
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* and concurrent fsync requests. Direct IO writes must acquire read
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* access on this semaphore for creating an extent map and its
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* corresponding ordered extent. The fast fsync path must acquire write
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* access on this semaphore before it collects ordered extents and
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* extent maps.
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*/
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struct rw_semaphore dio_sem;
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struct inode vfs_inode;
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};
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extern unsigned char btrfs_filetype_table[];
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static inline struct btrfs_inode *BTRFS_I(struct inode *inode)
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{
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return container_of(inode, struct btrfs_inode, vfs_inode);
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}
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static inline unsigned long btrfs_inode_hash(u64 objectid,
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const struct btrfs_root *root)
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{
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u64 h = objectid ^ (root->objectid * GOLDEN_RATIO_PRIME);
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#if BITS_PER_LONG == 32
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h = (h >> 32) ^ (h & 0xffffffff);
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#endif
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return (unsigned long)h;
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}
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static inline void btrfs_insert_inode_hash(struct inode *inode)
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{
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unsigned long h = btrfs_inode_hash(inode->i_ino, BTRFS_I(inode)->root);
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__insert_inode_hash(inode, h);
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}
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static inline u64 btrfs_ino(struct btrfs_inode *inode)
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{
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u64 ino = inode->location.objectid;
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/*
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* !ino: btree_inode
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* type == BTRFS_ROOT_ITEM_KEY: subvol dir
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*/
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if (!ino || inode->location.type == BTRFS_ROOT_ITEM_KEY)
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ino = inode->vfs_inode.i_ino;
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return ino;
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}
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static inline void btrfs_i_size_write(struct btrfs_inode *inode, u64 size)
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{
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i_size_write(&inode->vfs_inode, size);
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inode->disk_i_size = size;
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}
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static inline bool btrfs_is_free_space_inode(struct btrfs_inode *inode)
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{
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struct btrfs_root *root = inode->root;
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if (root == root->fs_info->tree_root &&
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btrfs_ino(inode) != BTRFS_BTREE_INODE_OBJECTID)
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return true;
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if (inode->location.objectid == BTRFS_FREE_INO_OBJECTID)
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return true;
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return false;
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}
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static inline int btrfs_inode_in_log(struct btrfs_inode *inode, u64 generation)
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{
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int ret = 0;
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spin_lock(&inode->lock);
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if (inode->logged_trans == generation &&
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inode->last_sub_trans <= inode->last_log_commit &&
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inode->last_sub_trans <= inode->root->last_log_commit) {
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/*
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* After a ranged fsync we might have left some extent maps
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* (that fall outside the fsync's range). So return false
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* here if the list isn't empty, to make sure btrfs_log_inode()
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* will be called and process those extent maps.
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*/
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smp_mb();
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if (list_empty(&inode->extent_tree.modified_extents))
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ret = 1;
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}
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spin_unlock(&inode->lock);
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return ret;
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}
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#define BTRFS_DIO_ORIG_BIO_SUBMITTED 0x1
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struct btrfs_dio_private {
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struct inode *inode;
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unsigned long flags;
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u64 logical_offset;
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u64 disk_bytenr;
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u64 bytes;
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void *private;
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/* number of bios pending for this dio */
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atomic_t pending_bios;
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/* IO errors */
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int errors;
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/* orig_bio is our btrfs_io_bio */
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struct bio *orig_bio;
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/* dio_bio came from fs/direct-io.c */
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struct bio *dio_bio;
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/*
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* The original bio may be split to several sub-bios, this is
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* done during endio of sub-bios
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*/
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int (*subio_endio)(struct inode *, struct btrfs_io_bio *, int);
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};
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/*
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* Disable DIO read nolock optimization, so new dio readers will be forced
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* to grab i_mutex. It is used to avoid the endless truncate due to
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* nonlocked dio read.
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*/
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static inline void btrfs_inode_block_unlocked_dio(struct btrfs_inode *inode)
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{
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set_bit(BTRFS_INODE_READDIO_NEED_LOCK, &inode->runtime_flags);
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smp_mb();
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}
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static inline void btrfs_inode_resume_unlocked_dio(struct btrfs_inode *inode)
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{
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smp_mb__before_atomic();
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clear_bit(BTRFS_INODE_READDIO_NEED_LOCK, &inode->runtime_flags);
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}
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static inline void btrfs_print_data_csum_error(struct btrfs_inode *inode,
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u64 logical_start, u32 csum, u32 csum_expected, int mirror_num)
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{
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struct btrfs_root *root = inode->root;
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/* Output minus objectid, which is more meaningful */
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if (root->objectid >= BTRFS_LAST_FREE_OBJECTID)
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btrfs_warn_rl(root->fs_info,
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"csum failed root %lld ino %lld off %llu csum 0x%08x expected csum 0x%08x mirror %d",
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root->objectid, btrfs_ino(inode),
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logical_start, csum, csum_expected, mirror_num);
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else
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btrfs_warn_rl(root->fs_info,
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"csum failed root %llu ino %llu off %llu csum 0x%08x expected csum 0x%08x mirror %d",
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root->objectid, btrfs_ino(inode),
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logical_start, csum, csum_expected, mirror_num);
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}
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bool btrfs_page_exists_in_range(struct inode *inode, loff_t start, loff_t end);
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#endif
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