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| author | Amir Goldstein <amir73il@gmail.com> | 2018-06-07 17:07:15 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-06-07 17:34:36 -0700 |
| commit | 12ba780d64f6c96d40de9c4d1468fb732e64be4c (patch) | |
| tree | e2761c1591c03a7268632f05c04e07568b01e58c /mm/shmem.c | |
| parent | 88484826bc67844eeae1855ebe32cce9edd937c9 (diff) | |
| download | lwn-12ba780d64f6c96d40de9c4d1468fb732e64be4c.tar.gz lwn-12ba780d64f6c96d40de9c4d1468fb732e64be4c.zip | |
tmpfs: allow decoding a file handle of an unlinked file
tmpfs uses the helper d_find_alias() to find a dentry from a decoded
inode, but d_find_alias() skips unhashed dentries, so unlinked files
cannot be decoded from a file handle.
This can be reproduced using xfstests test program open_by_handle:
$ open_by handle -c /tmp/testdir
$ open_by_handle -dk /tmp/testdir
open_by_handle(/tmp/testdir/file000000) returned 116 incorrectly on an unlinked open file!
To fix this, if d_find_alias() can't find a hashed alias, call
d_find_any_alias() to return an unhashed one.
Link: http://lkml.kernel.org/r/CAOQ4uxg+qSLP0KwdW+h1tcPqOCQd+_pGZVXiePQB1TXCMBMctQ@mail.gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: NeilBrown <neilb@suse.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jeff Layton <jlayton@poochiereds.net>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/shmem.c')
| -rw-r--r-- | mm/shmem.c | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/mm/shmem.c b/mm/shmem.c index 103f3d1040f8..9a1b553e30e0 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -3209,6 +3209,15 @@ static int shmem_match(struct inode *ino, void *vfh) return ino->i_ino == inum && fh[0] == ino->i_generation; } +/* Find any alias of inode, but prefer a hashed alias */ +static struct dentry *shmem_find_alias(struct inode *inode) +{ + struct dentry *alias = d_find_alias(inode); + + return alias ?: d_find_any_alias(inode); +} + + static struct dentry *shmem_fh_to_dentry(struct super_block *sb, struct fid *fid, int fh_len, int fh_type) { @@ -3225,7 +3234,7 @@ static struct dentry *shmem_fh_to_dentry(struct super_block *sb, inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]), shmem_match, fid->raw); if (inode) { - dentry = d_find_alias(inode); + dentry = shmem_find_alias(inode); iput(inode); } |