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authorAmir Goldstein <amir73il@gmail.com>2018-06-07 17:07:15 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-06-07 17:34:36 -0700
commit12ba780d64f6c96d40de9c4d1468fb732e64be4c (patch)
treee2761c1591c03a7268632f05c04e07568b01e58c /mm/shmem.c
parent88484826bc67844eeae1855ebe32cce9edd937c9 (diff)
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.c11
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);
}