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fanotify: Split fsid check from other fid mode checks

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FAN_FS_ERROR will require fsid, but not necessarily require the
filesystem to expose a file handle.  Split those checks into different
functions, so they can be used separately when setting up an event.

While there, update a comment about tmpfs having 0 fsid, which is no
longer true.

Link: https://lore.kernel.org/r/20211025192746.66445-7-krisman@collabora.com
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Gabriel Krisman Bertazi 2021-10-25 16:27:21 -03:00 committed by Jan Kara
parent b9928e80dd
commit 8299212cbd
1 changed files with 18 additions and 9 deletions
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27
fs/notify/fanotify/fanotify_user.c
View file

@ -1300,16 +1300,15 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
return fd;
}
/* Check if filesystem can encode a unique fid */
static int fanotify_test_fid(struct path *path, __kernel_fsid_t *fsid)
static int fanotify_test_fsid(struct dentry *dentry, __kernel_fsid_t *fsid)
{
__kernel_fsid_t root_fsid;
int err;
/*
* Make sure path is not in filesystem with zero fsid (e.g. tmpfs).
* Make sure dentry is not of a filesystem with zero fsid (e.g. fuse).
*/
err = vfs_get_fsid(path->dentry, fsid);
err = vfs_get_fsid(dentry, fsid);
if (err)
return err;
@ -1317,10 +1316,10 @@ static int fanotify_test_fid(struct path *path, __kernel_fsid_t *fsid)
return -ENODEV;
/*
* Make sure path is not inside a filesystem subvolume (e.g. btrfs)
* Make sure dentry is not of a filesystem subvolume (e.g. btrfs)
* which uses a different fsid than sb root.
*/
err = vfs_get_fsid(path->dentry->d_sb->s_root, &root_fsid);
err = vfs_get_fsid(dentry->d_sb->s_root, &root_fsid);
if (err)
return err;
@ -1328,6 +1327,12 @@ static int fanotify_test_fid(struct path *path, __kernel_fsid_t *fsid)
root_fsid.val[1] != fsid->val[1])
return -EXDEV;
return 0;
}
/* Check if filesystem can encode a unique fid */
static int fanotify_test_fid(struct dentry *dentry)
{
/*
* We need to make sure that the file system supports at least
* encoding a file handle so user can use name_to_handle_at() to
@ -1335,8 +1340,8 @@ static int fanotify_test_fid(struct path *path, __kernel_fsid_t *fsid)
* objects. However, name_to_handle_at() requires that the
* filesystem also supports decoding file handles.
*/
if (!path->dentry->d_sb->s_export_op ||
!path->dentry->d_sb->s_export_op->fh_to_dentry)
if (!dentry->d_sb->s_export_op ||
!dentry->d_sb->s_export_op->fh_to_dentry)
return -EOPNOTSUPP;
return 0;
@ -1487,7 +1492,11 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
}
if (fid_mode) {
ret = fanotify_test_fid(&path, &__fsid);
ret = fanotify_test_fsid(path.dentry, &__fsid);
if (ret)
goto path_put_and_out;
ret = fanotify_test_fid(path.dentry);
if (ret)
goto path_put_and_out;