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); } _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
