The patch titled
Subject: tmpfs: allow decoding a file handle of an unlinked file
has been added to the -mm tree. Its filename is
tmpfs-allow-decoding-a-file-handle-of-an-unlinked-file.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/tmpfs-allow-decoding-a-file-handle-of-an-unlinked-file.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/tmpfs-allow-decoding-a-file-handle-of-an-unlinked-file.patch
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------------------------------------------------------
From: Amir Goldstein <amir73il@xxxxxxxxx>
Subject: 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@xxxxxxxxxxxxxx
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
Reviewed-by: NeilBrown <neilb@xxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Jeff Layton <jlayton@xxxxxxxxxxxxxxx>
Cc: "J. Bruce Fields" <bfields@xxxxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/shmem.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff -puN mm/shmem.c~tmpfs-allow-decoding-a-file-handle-of-an-unlinked-file mm/shmem.c
--- a/mm/shmem.c~tmpfs-allow-decoding-a-file-handle-of-an-unlinked-file
+++ a/mm/shmem.c
@@ -3209,6 +3209,15 @@ static int shmem_match(struct inode *ino
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
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);
}
_
Patches currently in -mm which might be from amir73il@xxxxxxxxx are
tmpfs-allow-decoding-a-file-handle-of-an-unlinked-file.patch
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