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4751832da9
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Qu Wenruo 4751832da9 btrfs: fiemap: Cache and merge fiemap extent before submit it to user 
[BUG]
Cycle mount btrfs can cause fiemap to return different result.
Like:
 # mount /dev/vdb5 /mnt/btrfs
 # dd if=/dev/zero bs=16K count=4 oflag=dsync of=/mnt/btrfs/file
 # xfs_io -c "fiemap -v" /mnt/btrfs/file
 /mnt/test/file:
 EXT: FILE-OFFSET      BLOCK-RANGE      TOTAL FLAGS
   0: [0..127]:        25088..25215       128   0x1
 # umount /mnt/btrfs
 # mount /dev/vdb5 /mnt/btrfs
 # xfs_io -c "fiemap -v" /mnt/btrfs/file
 /mnt/test/file:
 EXT: FILE-OFFSET      BLOCK-RANGE      TOTAL FLAGS
   0: [0..31]:         25088..25119        32   0x0
   1: [32..63]:        25120..25151        32   0x0
   2: [64..95]:        25152..25183        32   0x0
   3: [96..127]:       25184..25215        32   0x1
But after above fiemap, we get correct merged result if we call fiemap
again.
 # xfs_io -c "fiemap -v" /mnt/btrfs/file
 /mnt/test/file:
 EXT: FILE-OFFSET      BLOCK-RANGE      TOTAL FLAGS
   0: [0..127]:        25088..25215       128   0x1

[REASON]
Btrfs will try to merge extent map when inserting new extent map.

btrfs_fiemap(start=0 len=(u64)-1)
|- extent_fiemap(start=0 len=(u64)-1)
   |- get_extent_skip_holes(start=0 len=64k)
   |  |- btrfs_get_extent_fiemap(start=0 len=64k)
   |     |- btrfs_get_extent(start=0 len=64k)
   |        |  Found on-disk (ino, EXTENT_DATA, 0)
   |        |- add_extent_mapping()
   |        |- Return (em->start=0, len=16k)
   |
   |- fiemap_fill_next_extent(logic=0 phys=X len=16k)
   |
   |- get_extent_skip_holes(start=0 len=64k)
   |  |- btrfs_get_extent_fiemap(start=0 len=64k)
   |     |- btrfs_get_extent(start=16k len=48k)
   |        |  Found on-disk (ino, EXTENT_DATA, 16k)
   |        |- add_extent_mapping()
   |        |  |- try_merge_map()
   |        |     Merge with previous em start=0 len=16k
   |        |     resulting em start=0 len=32k
   |        |- Return (em->start=0, len=32K)    << Merged result
   |- Stripe off the unrelated range (0~16K) of return em
   |- fiemap_fill_next_extent(logic=16K phys=X+16K len=16K)
      ^^^ Causing split fiemap extent.

And since in add_extent_mapping(), em is already merged, in next
fiemap() call, we will get merged result.

[FIX]
Here we introduce a new structure, fiemap_cache, which records previous
fiemap extent.

And will always try to merge current fiemap_cache result before calling
fiemap_fill_next_extent().
Only when we failed to merge current fiemap extent with cached one, we
will call fiemap_fill_next_extent() to submit cached one.

So by this method, we can merge all fiemap extents.

It can also be done in fs/ioctl.c, however the problem is if
fieinfo->fi_extents_max == 0, we have no space to cache previous fiemap
extent.
So I choose to merge it in btrfs.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2017-05-16 15:41:53 +02:00
..
9p Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-03-03 21:44:35 -08:00
adfs
affs sched/headers: Prepare to remove <linux/cred.h> inclusion from <linux/sched.h> 2017-03-02 08:42:31 +01:00
afs afs: Don't wait for page writeback with the page lock held 2017-03-16 16:29:30 +00:00
autofs4 sched/headers: Prepare to remove <linux/cred.h> inclusion from <linux/sched.h> 2017-03-02 08:42:31 +01:00
befs sched/headers: Prepare to remove <linux/cred.h> inclusion from <linux/sched.h> 2017-03-02 08:42:31 +01:00
bfs Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
btrfs btrfs: fiemap: Cache and merge fiemap extent before submit it to user 2017-05-16 15:41:53 +02:00
cachefiles sched/headers: Prepare to remove <linux/cred.h> inclusion from <linux/sched.h> 2017-03-02 08:42:31 +01:00
ceph Merge branch 'rebased-statx' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-03-03 11:38:56 -08:00
cifs CIFS: Fix SMB3 mount without specifying a security mechanism 2017-04-13 10:03:26 -05:00
coda Merge branch 'rebased-statx' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-03-03 11:38:56 -08:00
configfs Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
cramfs
crypto A code cleanup and bugfix for fs/crypto. 2017-03-25 15:36:56 -07:00
debugfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2017-02-23 20:33:51 -08:00
devpts
dlm net: Work around lockdep limitation in sockets that use sockets 2017-03-09 18:23:27 -08:00
ecryptfs Merge branch 'rebased-statx' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-03-03 11:38:56 -08:00
efivarfs
efs Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
exofs locking/atomic, kref: Add kref_read() 2017-01-14 11:37:18 +01:00
exportfs Merge branch 'rebased-statx' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-03-03 11:38:56 -08:00
ext2 sched/headers: Prepare to remove <linux/cred.h> inclusion from <linux/sched.h> 2017-03-02 08:42:31 +01:00
ext4 statx: Include a mask for stx_attributes in struct statx 2017-04-03 01:06:00 -04:00
f2fs f2fs: combine nat_bits and free_nid_bitmap cache 2017-03-20 10:00:18 -04:00
fat fat: fix using uninitialized fields of fat_inode/fsinfo_inode 2017-03-09 17:01:10 -08:00
freevxfs
fscache KEYS: Differentiate uses of rcu_dereference_key() and user_key_payload() 2017-03-02 10:09:00 +11:00
fuse Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse 2017-03-03 12:14:13 -08:00
gfs2 gfs2: Avoid alignment hole in struct lm_lockname 2017-03-15 10:06:07 -04:00
hfs Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-03-03 21:44:35 -08:00
hfsplus sched/headers: Prepare to remove <linux/cred.h> inclusion from <linux/sched.h> 2017-03-02 08:42:31 +01:00
hostfs
hpfs sched/headers: Prepare to move signal wakeup & sigpending methods from <linux/sched.h> into <linux/sched/signal.h> 2017-03-02 08:42:32 +01:00
hugetlbfs hugetlbfs: fix offset overflow in hugetlbfs mmap 2017-04-13 18:24:21 -07:00
isofs sched/headers: Prepare to remove <linux/cred.h> inclusion from <linux/sched.h> 2017-03-02 08:42:31 +01:00
jbd2 jbd2: don't leak memory if setting up journal fails 2017-03-15 15:08:48 -04:00
jffs2 sched/headers: Prepare to move signal wakeup & sigpending methods from <linux/sched.h> into <linux/sched/signal.h> 2017-03-02 08:42:32 +01:00
jfs fs: add i_blocksize() 2017-02-27 18:43:46 -08:00
kernfs kernfs: Check KERNFS_HAS_RELEASE before calling kernfs_release_file() 2017-03-17 10:25:59 +09:00
lockd sched/headers: Prepare for new header dependencies before moving code to <linux/sched/signal.h> 2017-03-02 08:42:29 +01:00
minix statx: Add a system call to make enhanced file info available 2017-03-02 20:51:15 -05:00
ncpfs Merge branch 'WIP.sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-03-03 10:16:38 -08:00
nfs NFS client fixes for 4.11 (part 2) 2017-03-31 12:29:03 -07:00
nfs_common
nfsd NFSD: fix nfsd_reset_versions for NFSv4. 2017-03-10 17:04:50 -05:00
nilfs2 sched/headers: Prepare to move signal wakeup & sigpending methods from <linux/sched.h> into <linux/sched/signal.h> 2017-03-02 08:42:32 +01:00
nls
notify sched/headers: Prepare to move signal wakeup & sigpending methods from <linux/sched.h> into <linux/sched/signal.h> 2017-03-02 08:42:32 +01:00
ntfs sched/headers: Prepare to move signal wakeup & sigpending methods from <linux/sched.h> into <linux/sched/signal.h> 2017-03-02 08:42:32 +01:00
ocfs2 net: Work around lockdep limitation in sockets that use sockets 2017-03-09 18:23:27 -08:00
omfs sched/headers: Prepare to remove <linux/cred.h> inclusion from <linux/sched.h> 2017-03-02 08:42:31 +01:00
openpromfs Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
orangefs orangefs: free superblock when mount fails 2017-04-15 09:39:31 -07:00
overlayfs overlayfs: remove now unnecessary header file include 2017-03-08 10:42:13 -08:00
proc thp: fix MADV_DONTNEED vs clear soft dirty race 2017-04-13 18:24:21 -07:00
pstore fs/pstore: fs/squashfs: change usage of LZ4 to work with new LZ4 version 2017-02-24 17:46:57 -08:00
qnx4
qnx6
quota sched/headers: Prepare to remove <linux/cred.h> inclusion from <linux/sched.h> 2017-03-02 08:42:31 +01:00
ramfs Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
reiserfs fs: add i_blocksize() 2017-02-27 18:43:46 -08:00
romfs romfs: use different way to generate fsid for BLOCK or MTD 2017-01-24 16:26:14 -08:00
squashfs fs/pstore: fs/squashfs: change usage of LZ4 to work with new LZ4 version 2017-02-24 17:46:57 -08:00
sysfs sysfs: be careful of error returns from ops->show() 2017-04-08 17:33:32 +02:00
sysv statx: Add a system call to make enhanced file info available 2017-03-02 20:51:15 -05:00
tracefs
ubifs statx: Add a system call to make enhanced file info available 2017-03-02 20:51:15 -05:00
udf statx: Add a system call to make enhanced file info available 2017-03-02 20:51:15 -05:00
ufs Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
xfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-04-09 08:26:21 -07:00
aio.c Merge branch 'WIP.sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-03-03 10:16:38 -08:00
anon_inodes.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
attr.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/signal.h> 2017-03-02 08:42:29 +01:00
bad_inode.c statx: Add a system call to make enhanced file info available 2017-03-02 20:51:15 -05:00
binfmt_aout.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task_stack.h> 2017-03-02 08:42:36 +01:00
binfmt_elf_fdpic.c sched/headers: Prepare to move cputime functionality from <linux/sched.h> into <linux/sched/cputime.h> 2017-03-02 08:42:39 +01:00
binfmt_elf.c sched/headers: Prepare to move cputime functionality from <linux/sched.h> into <linux/sched/cputime.h> 2017-03-02 08:42:39 +01:00
binfmt_em86.c
binfmt_flat.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task_stack.h> 2017-03-02 08:42:36 +01:00
binfmt_misc.c sched/headers: Prepare to remove the <linux/mm_types.h> dependency from <linux/sched.h> 2017-03-02 08:42:37 +01:00
binfmt_script.c
block_dev.c block: Initialize bd_bdi on inode initialization 2017-03-02 08:56:59 -07:00
buffer.c sched/headers: Prepare for the reduction of <linux/sched.h>'s signal API dependency 2017-03-02 08:42:37 +01:00
char_dev.c
compat_binfmt_elf.c fs/binfmt: Convert obsolete cputime type to nsecs 2017-02-01 09:13:51 +01:00
compat_ioctl.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
compat.c sched/headers: Prepare to remove <linux/cred.h> inclusion from <linux/sched.h> 2017-03-02 08:42:31 +01:00
coredump.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task_stack.h> 2017-03-02 08:42:36 +01:00
dax.c dax: fix radix tree insertion race 2017-04-08 00:47:49 -07:00
dcache.c mnt: Protect the mountpoint hashtable with mount_lock 2017-01-10 13:34:43 +13:00
dcookies.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
direct-io.c fs: add i_blocksize() 2017-02-27 18:43:46 -08:00
drop_caches.c
eventfd.c sched/headers: Prepare to move signal wakeup & sigpending methods from <linux/sched.h> into <linux/sched/signal.h> 2017-03-02 08:42:32 +01:00
eventpoll.c sched/headers: Prepare to move signal wakeup & sigpending methods from <linux/sched.h> into <linux/sched/signal.h> 2017-03-02 08:42:32 +01:00
exec.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task.h> 2017-03-02 08:42:35 +01:00
fcntl.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task.h> 2017-03-02 08:42:35 +01:00
fhandle.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
file_table.c sched/headers: Prepare to remove <linux/cred.h> inclusion from <linux/sched.h> 2017-03-02 08:42:31 +01:00
file.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/signal.h> 2017-03-02 08:42:29 +01:00
filesystems.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
fs_pin.c
fs_struct.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task.h> 2017-03-02 08:42:35 +01:00
fs-writeback.c writeback: fix memory leak in wb_queue_work() 2017-03-13 08:27:34 -06:00
inode.c
internal.h iomap: constify struct iomap_ops 2017-01-30 16:32:25 -08:00
ioctl.c sched/headers: Prepare for the reduction of <linux/sched.h>'s signal API dependency 2017-03-02 08:42:37 +01:00
iomap.c iomap: invalidate page caches should be after iomap_dio_complete() in direct write 2017-03-06 09:50:01 -08:00
Kconfig dax: fix build warnings with FS_DAX and !FS_IOMAP 2017-01-24 16:26:14 -08:00
Kconfig.binfmt
libfs.c Merge branch 'rebased-statx' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-03-03 11:38:56 -08:00
locks.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
Makefile logfs: remove from tree 2016-12-14 23:48:11 -05:00
mbcache.c
mount.h mnt: Tuck mounts under others instead of creating shadow/side mounts. 2017-02-04 00:01:06 +13:00
mpage.c fs: add i_blocksize() 2017-02-27 18:43:46 -08:00
namei.c vfs: don't do RCU lookup of empty pathnames 2017-04-15 09:34:52 -07:00
namespace.c sched/headers: Prepare to move 'init_task' and 'init_thread_union' from <linux/sched.h> to <linux/sched/task.h> 2017-03-02 08:42:38 +01:00
no-block.c
nsfs.c nsfs: Add an ioctl() to return owner UID of a userns 2017-02-03 14:35:43 +13:00
open.c vfs: wrap write f_ops with file_{start,end}_write() 2017-02-07 15:05:04 +01:00
pipe.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
pnode.c mnt: Tuck mounts under others instead of creating shadow/side mounts. 2017-02-04 00:01:06 +13:00
pnode.h mnt: Tuck mounts under others instead of creating shadow/side mounts. 2017-02-04 00:01:06 +13:00
posix_acl.c sched/headers: Prepare to remove <linux/cred.h> inclusion from <linux/sched.h> 2017-03-02 08:42:31 +01:00
proc_namespace.c sched/headers: Prepare to move the task_lock()/unlock() APIs to <linux/sched/task.h> 2017-03-02 08:42:38 +01:00
read_write.c Merge branch 'WIP.sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-03-03 10:16:38 -08:00
readdir.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
select.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/signal.h> 2017-03-02 08:42:29 +01:00
seq_file.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
signalfd.c
splice.c Merge branch 'WIP.sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-03-03 10:16:38 -08:00
stack.c
stat.c statx: Include a mask for stx_attributes in struct statx 2017-04-03 01:06:00 -04:00
statfs.c
super.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2017-02-23 20:33:51 -08:00
sync.c vfs: use helper for calling f_op->fsync() 2017-02-20 16:51:23 +01:00
timerfd.c timerfd: Only check CAP_WAKE_ALARM when it is needed 2017-03-01 12:53:44 +01:00
userfaultfd.c userfaultfd: report actual registered features in fdinfo 2017-04-08 00:47:48 -07:00
utimes.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
xattr.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00