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407cd7fb83
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Tahsin Erdogan 407cd7fb83 ext4: change fast symlink test to not rely on i_blocks 
ext4_inode_info->i_data is the storage area for 4 types of data:

  a) Extents data
  b) Inline data
  c) Block map
  d) Fast symlink data (symlink length < 60)

Extents data case is positively identified by EXT4_INODE_EXTENTS flag.
Inline data case is also obvious because of EXT4_INODE_INLINE_DATA
flag.

Distinguishing c) and d) however requires additional logic. This
currently relies on i_blocks count. After subtracting external xattr
block from i_blocks, if it is greater than 0 then we know that some
data blocks exist, so there must be a block map.

This logic got broken after ea_inode feature was added. That feature
charges the data blocks of external xattr inodes to the referencing
inode and so adds them to the i_blocks. To fix this, we could subtract
ea_inode blocks by iterating through all xattr entries and then check
whether remaining i_blocks count is zero. Besides being complicated,
this won't change the fact that the current way of distinguishing
between c) and d) is fragile.

The alternative solution is to test whether i_size is less than 60 to
determine fast symlink case. ext4_symlink() uses the same test to decide
whether to store the symlink in i_data. There is one caveat to address
before this can work though.

If an inode's i_nlink is zero during eviction, its i_size is set to
zero and its data is truncated. If system crashes before inode is removed
from the orphan list, next boot orphan cleanup may find the inode with
zero i_size. So, a symlink that had its data stored in a block may now
appear to be a fast symlink. The solution used in this patch is to treat
i_size = 0 as a non-fast symlink case. A zero sized symlink is not legal
so the only time this can happen is the mentioned scenario. This is also
logically correct because a i_size = 0 symlink has no data stored in
i_data.

Suggested-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Tahsin Erdogan <tahsin@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
2017-07-04 00:11:21 -04:00
..
9p 9p: Convert to separately allocated bdi 2017-04-20 12:09:55 -06:00
adfs
affs fs/affs: add rename exchange 2017-05-05 15:24:52 -04:00
afs Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2017-05-02 16:40:27 -07:00
autofs4 Fix dead URLs to ftp.kernel.org 2017-03-28 16:16:52 +02:00
befs befs: make export work with cold dcache 2017-05-05 11:35:35 +01:00
bfs Tigran has moved 2017-05-12 15:57:15 -07:00
btrfs Merge branch 'for-linus-4.12' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs 2017-05-10 08:33:17 -07:00
cachefiles sched/headers: Prepare to remove <linux/cred.h> inclusion from <linux/sched.h> 2017-03-02 08:42:31 +01:00
ceph The two main items are support for disabling automatic rbd exclusive 2017-05-10 08:42:33 -07:00
cifs [CIFS] Minor cleanup of xattr query function 2017-05-12 20:59:10 -05:00
coda coda: Convert to separately allocated bdi 2017-04-20 12:09:55 -06:00
configfs Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
cramfs
crypto fscrypt: introduce helper function for filename matching 2017-05-04 11:44:37 -04:00
debugfs fs: constify tree_descr arrays passed to simple_fill_super() 2017-04-26 23:54:06 -04:00
devpts
dlm net: Work around lockdep limitation in sockets that use sockets 2017-03-09 18:23:27 -08:00
ecryptfs ecryptfs: Convert to separately allocated bdi 2017-04-20 12:09:55 -06:00
efivarfs
efs Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
exofs fs: semove set but not checked AOP_FLAG_UNINTERRUPTIBLE flag 2017-05-08 17:15:14 -07:00
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 ext2, ext4: make mb block cache names more explicit 2017-06-22 11:28:55 -04:00
ext4 ext4: change fast symlink test to not rely on i_blocks 2017-07-04 00:11:21 -04:00
f2fs Merge branch 'akpm' (patches from Andrew) 2017-05-08 18:17:56 -07:00
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.dk/linux-block 2017-05-20 16:12:30 -07:00
gfs2 gfs2: replace CURRENT_TIME with current_time 2017-05-08 17:15:15 -07:00
hfs fs: semove set but not checked AOP_FLAG_UNINTERRUPTIBLE flag 2017-05-08 17:15:14 -07:00
hfsplus fs: semove set but not checked AOP_FLAG_UNINTERRUPTIBLE flag 2017-05-08 17:15:14 -07:00
hostfs vfs: remove ".readlink = generic_readlink" assignments 2016-12-09 16:45:04 +01:00
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: preserve original nofs flag during journal restart 2017-05-21 22:32:23 -04:00
jffs2 jffs2: fix spelling mistake: "requestied" -> "requested" 2017-04-19 11:35:55 -07:00
jfs jfs: Remove jfs_get_inode_flags() 2017-04-19 14:21:23 +02:00
kernfs kernfs: Check KERNFS_HAS_RELEASE before calling kernfs_release_file() 2017-03-17 10:25:59 +09:00
lockd Another RDMA update from Chuck Lever, and a bunch of miscellaneous 2017-05-10 13:29:23 -07:00
minix statx: Add a system call to make enhanced file info available 2017-03-02 20:51:15 -05:00
ncpfs ncpfs: Convert to separately allocated bdi 2017-04-20 12:09:55 -06:00
nfs Another RDMA update from Chuck Lever, and a bunch of miscellaneous 2017-05-10 13:29:23 -07:00
nfs_common
nfsd Another RDMA update from Chuck Lever, and a bunch of miscellaneous 2017-05-10 13:29:23 -07:00
nilfs2 fs: Remove SB_I_DYNBDI flag 2017-04-20 12:09:55 -06:00
nls
notify fanotify: don't expose EOPENSTALE to userspace 2017-04-25 15:48:06 +02:00
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 fs/ocfs2/cluster: use offset_in_page() macro 2017-05-03 15:52:07 -07:00
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 Some cleanups: 2017-05-05 13:36:10 -07:00
overlayfs Merge branch 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs 2017-05-10 09:03:48 -07:00
proc proc: try to remove use of FOLL_FORCE entirely 2017-05-09 08:45:16 -07:00
pstore Annotation of module parameters that specify device settings 2017-05-10 19:13:03 -07:00
qnx4
qnx6
quota quota: add get_inode_usage callback to transfer multi-inode charges 2017-06-22 11:46:48 -04:00
ramfs Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
reiserfs reiserfs: use designated initializers 2017-05-08 17:15:11 -07:00
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 fs: constify tree_descr arrays passed to simple_fill_super() 2017-04-26 23:54:06 -04:00
ubifs This pull request contains updates for both UBI and UBIFS: 2017-05-13 10:23:12 -07:00
udf udf: use kmap_atomic for memcpy copying 2017-04-24 16:28:02 +02:00
ufs fs: ufs: use ktime_get_real_ts64() for birthtime 2017-05-08 17:15:15 -07:00
xfs dax, xfs, ext4: compile out iomap-dax paths in the FS_DAX=n case 2017-05-13 17:52:16 -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 fs: constify tree_descr arrays passed to simple_fill_super() 2017-04-26 23:54:06 -04:00
binfmt_script.c
block_dev.c Merge branch 'libnvdimm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm 2017-05-12 15:43:10 -07:00
buffer.c Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-05-09 09:12:53 -07:00
char_dev.c chardev: add helper function to register char devs with a struct device 2017-03-21 06:44:32 +01:00
compat_binfmt_elf.c fs/binfmt: Convert obsolete cputime type to nsecs 2017-02-01 09:13:51 +01:00
compat_ioctl.c fs: compat: Remove warning from COMPATIBLE_IOCTL 2017-04-29 17:47:19 -04:00
compat.c fs/compat.c: trim unused includes 2017-04-17 12:52:27 -04:00
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 Merge branch 'akpm' (patches from Andrew) 2017-05-13 09:49:35 -07:00
dcache.c fs: don't set *REFERENCED on single use objects 2017-05-03 11:47:05 -04:00
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 epoll: Add busy poll support to epoll with socket fds. 2017-03-24 20:49:31 -07:00
exec.c x86/arch_prctl: Add ARCH_[GET|SET]_CPUID 2017-03-20 16:10:34 +01:00
fcntl.c Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-05-09 09:12:53 -07:00
fhandle.c fhandle: move compat syscalls from compat.c 2017-04-17 12:52:26 -04:00
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 mm, vmalloc: use __GFP_HIGHMEM implicitly 2017-05-08 17:15:13 -07:00
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 Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-05-09 09:12:53 -07:00
internal.h Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-05-09 09:12:53 -07:00
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 fs: semove set but not checked AOP_FLAG_UNINTERRUPTIBLE flag 2017-05-08 17:15:14 -07:00
Kconfig block, dax: move "select DAX" from BLOCK to FS_DAX 2017-05-08 10:55:27 -07:00
Kconfig.binfmt
libfs.c fs: constify tree_descr arrays passed to simple_fill_super() 2017-04-26 23:54:06 -04:00
locks.c locks: Set FL_CLOSE when removing flock locks on close() 2017-04-21 10:45:01 -04:00
Makefile logfs: remove from tree 2016-12-14 23:48:11 -05:00
mbcache.c ext4: xattr inode deduplication 2017-06-22 11:44:55 -04:00
mount.h fsnotify: Free fsnotify_mark_connector when there is no mark attached 2017-04-10 17:37:35 +02:00
mpage.c fs: add i_blocksize() 2017-02-27 18:43:46 -08:00
namei.c Merge branch 'work.sane_pwd' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-05-12 11:39:59 -07:00
namespace.c Merge branch 'work.sane_pwd' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-05-12 11:39:59 -07:00
no-block.c
nsfs.c ns: allow ns_entries to have custom symlink content 2017-05-08 17:15:12 -07:00
open.c Merge branch 'work.sane_pwd' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-05-12 11:39:59 -07:00
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 move compat_rw_copy_check_uvector() over to fs/read_write.c 2017-04-17 12:52:26 -04:00
readdir.c readdir: move compat syscalls from compat.c 2017-04-17 12:52:24 -04:00
select.c treewide: use kv[mz]alloc* rather than opencoded variants 2017-05-08 17:15:13 -07:00
seq_file.c mm: introduce kv[mz]alloc helpers 2017-05-08 17:15:12 -07:00
signalfd.c mm: Rename SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY_RCU 2017-04-18 11:42:36 -07:00
splice.c Merge branch 'work.splice' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-05-02 11:38:06 -07:00
stack.c
stat.c Merge branch 'work.compat' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-05-02 11:54:26 -07:00
statfs.c statfs: move compat syscalls from compat.c 2017-04-17 12:52:23 -04:00
super.c bdi: Drop 'parent' argument from bdi_register[_va]() 2017-04-20 12:09:55 -06:00
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 utimes: move compat syscalls from compat.c 2017-04-17 12:52:23 -04:00
xattr.c treewide: use kv[mz]alloc* rather than opencoded variants 2017-05-08 17:15:13 -07:00