diff options
| author | Li Wang <liwang@redhat.com> | 2018-12-17 15:10:38 +0800 |
|---|---|---|
| committer | Petr Vorel <pvorel@suse.cz> | 2019-01-28 16:35:36 +0100 |
| commit | 32c06126f1a444ce21e8464bf3261ad475a52ee0 (patch) | |
| tree | 9fd896e41a882dff6220bd299fe07c1bc7cece1e /include | |
| parent | b5f924a5c029d0bf7e53a93b04b68f83e6aa8215 (diff) | |
fcntl: fcntl F_SETLEASE return EAGAIN on overlapfs
>From Miklos's words:
The F_SETLEASE "failure" is caused by the simplistic way the
kernel currently determines if there's a possible local conflict
to a write lock:
check_conflicting_open(const struct dentry *dentry, const long arg, int flags)
{
/*...*/
if ((arg == F_WRLCK) && ((d_count(dentry) > 1) ||
(atomic_read(&inode->i_count) > 1)))
ret = -EAGAIN;
/*...*/
It reads the dentry count, and if there's any other reference
to the dentry or inode as the one held by this file, then it
is assumed to come from a conflicting open. Which is not true,
dentry references can come from variety of sources (e.g. O_PATH
opens are obviously non-conflicting). This causes failure on
tmpfs as well, which holds an extra reference on each dentry.
The extra ref on the dentry in overlayfs comes from the realfile
stored in the overlay file's private_data field.
The proper solution to this is probably to have an i_readcount,
matching the functionality of i_writecount, which would solve
the other problems with the current approach.
Note: this is not a failure in the sense that applications must
be written with the assumption that F_SETLEASE can fail with
-EAGAIN, so this error condition just makes the lease non-useful,
but shouldn't break anything.
Reviewed-by: Petr Vorel <pvorel@suse.cz>
==== Error log =====
fcntl24 1 TFAIL : fcntl24.c:148: fcntl(tfile_7254, F_SETLEASE, F_WRLCK) Failed, errno=11 : Resource temporarily unavailable
fcntl25 1 TFAIL : fcntl25.c:149: fcntl(tfile_7255, F_SETLEASE, F_WRLCK) Failed, errno=11 : Resource temporarily unavailable
fcntl26 1 TFAIL : fcntl26.c:149: fcntl(tfile_7256, F_SETLEASE, F_WRLCK) Failed, errno=11 : Resource temporarily unavailable
fcntl33.c:118: FAIL: fcntl() failed to set lease: EAGAIN/EWOULDBLOCK
fcntl33.c:118: FAIL: fcntl() failed to set lease: EAGAIN/EWOULDBLOCK
fcntl33.c:118: FAIL: fcntl() failed to set lease: EAGAIN/EWOULDBLOCK
fcntl33.c:118: FAIL: fcntl() failed to set lease: EAGAIN/EWOULDBLOCK
Reported-by: Xiong Zhou <xzhou@redhat.com>
Signed-off-by: Li Wang <liwang@redhat.com>
Cc: Miklos Szeredi <mszeredi@redhat.com>
Cc: Ye Chao <cye@redhat.com>
Signed-off-by: Petr Vorel <pvorel@suse.cz>
Diffstat (limited to 'include')
| -rw-r--r-- | include/tst_fs.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/tst_fs.h b/include/tst_fs.h index 8d3f1cfbc..23f139ded 100644 --- a/include/tst_fs.h +++ b/include/tst_fs.h @@ -41,6 +41,7 @@ #define TST_F2FS_MAGIC 0xF2F52010 #define TST_NILFS_MAGIC 0x3434 #define TST_EXOFS_MAGIC 0x5DF5 +#define TST_OVERLAYFS_MAGIC 0x794c7630 enum { TST_BYTES = 1, |