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zfs_rename: restructure to have cleaner fallbacks

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This is in preparation for RENAME_EXCHANGE and RENAME_WHITEOUT support
for ZoL, but the changes here allow for far nicer fallbacks than the
previous implementation (the source and target are re-linked in case of
the final link failing).

In addition, a small cleanup was done for the "target exists but is a
different type" codepath so that it's more understandable.

Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
Closes #12209
Closes #14070
This commit is contained in:
Aleksa Sarai
2019-04-26 23:23:07 +10:00
committed by Brian Behlendorf
parent 7b3ba29654
commit e015d6cc0b
3 changed files with 140 additions and 77 deletions
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module/os/linux/zfs/zfs_vnops_os.c
+69 -52
View File
@@ -2876,16 +2876,12 @@ top:
/*
* Source and target must be the same type.
*/
if (S_ISDIR(ZTOI(szp)->i_mode)) {
if (!S_ISDIR(ZTOI(tzp)->i_mode)) {
error = SET_ERROR(ENOTDIR);
goto out;
}
} else {
if (S_ISDIR(ZTOI(tzp)->i_mode)) {
error = SET_ERROR(EISDIR);
goto out;
}
boolean_t s_is_dir = S_ISDIR(ZTOI(szp)->i_mode) != 0;
boolean_t t_is_dir = S_ISDIR(ZTOI(tzp)->i_mode) != 0;
if (s_is_dir != t_is_dir) {
error = SET_ERROR(s_is_dir ? ENOTDIR : EISDIR);
goto out;
}
/*
* POSIX dictates that when the source and target
@@ -2941,51 +2937,49 @@ top:
return (error);
}
if (tzp) /* Attempt to remove the existing target */
/*
* Unlink the source.
*/
szp->z_pflags |= ZFS_AV_MODIFIED;
if (tdzp->z_pflags & ZFS_PROJINHERIT)
szp->z_pflags |= ZFS_PROJINHERIT;
error = sa_update(szp->z_sa_hdl, SA_ZPL_FLAGS(zfsvfs),
(void *)&szp->z_pflags, sizeof (uint64_t), tx);
ASSERT0(error);
error = zfs_link_destroy(sdl, szp, tx, ZRENAMING, NULL);
if (error)
goto commit;
/*
* Unlink the target.
*/
if (tzp) {
error = zfs_link_destroy(tdl, tzp, tx, zflg, NULL);
if (error == 0) {
error = zfs_link_create(tdl, szp, tx, ZRENAMING);
if (error == 0) {
szp->z_pflags |= ZFS_AV_MODIFIED;
if (tdzp->z_pflags & ZFS_PROJINHERIT)
szp->z_pflags |= ZFS_PROJINHERIT;
error = sa_update(szp->z_sa_hdl, SA_ZPL_FLAGS(zfsvfs),
(void *)&szp->z_pflags, sizeof (uint64_t), tx);
ASSERT0(error);
error = zfs_link_destroy(sdl, szp, tx, ZRENAMING, NULL);
if (error == 0) {
zfs_log_rename(zilog, tx, TX_RENAME |
(flags & FIGNORECASE ? TX_CI : 0), sdzp,
sdl->dl_name, tdzp, tdl->dl_name, szp);
} else {
/*
* At this point, we have successfully created
* the target name, but have failed to remove
* the source name. Since the create was done
* with the ZRENAMING flag, there are
* complications; for one, the link count is
* wrong. The easiest way to deal with this
* is to remove the newly created target, and
* return the original error. This must
* succeed; fortunately, it is very unlikely to
* fail, since we just created it.
*/
VERIFY3U(zfs_link_destroy(tdl, szp, tx,
ZRENAMING, NULL), ==, 0);
}
} else {
/*
* If we had removed the existing target, subsequent
* call to zfs_link_create() to add back the same entry
* but, the new dnode (szp) should not fail.
*/
ASSERT(tzp == NULL);
}
if (error)
goto commit_link_szp;
}
/*
* Create a new link at the target.
*/
error = zfs_link_create(tdl, szp, tx, ZRENAMING);
if (error) {
/*
* If we have removed the existing target, a subsequent call to
* zfs_link_create() to add back the same entry, but with a new
* dnode (szp), should not fail.
*/
ASSERT3P(tzp, ==, NULL);
goto commit_link_tzp;
}
zfs_log_rename(zilog, tx, TX_RENAME |
(flags & FIGNORECASE ? TX_CI : 0), sdzp,
sdl->dl_name, tdzp, tdl->dl_name, szp);
commit:
dmu_tx_commit(tx);
out:
if (zl != NULL)
@@ -3013,6 +3007,29 @@ out:
zfs_exit(zfsvfs, FTAG);
return (error);
/*
* Clean-up path for broken link state.
*
* At this point we are in a (very) bad state, so we need to do our
* best to correct the state. In particular, the nlink of szp is wrong
* because we were destroying and creating links with ZRENAMING.
*
* link_create()s are allowed to fail (though they shouldn't because we
* only just unlinked them and are putting the entries back during
* clean-up). But if they fail, we can just forcefully drop the nlink
* value to (at the very least) avoid broken nlink values -- though in
* the case of non-empty directories we will have to panic.
*/
commit_link_tzp:
if (tzp) {
if (zfs_link_create(tdl, tzp, tx, ZRENAMING))
VERIFY3U(zfs_drop_nlink(tzp, tx, NULL), ==, 0);
}
commit_link_szp:
if (zfs_link_create(sdl, szp, tx, ZRENAMING))
VERIFY3U(zfs_drop_nlink(szp, tx, NULL), ==, 0);
goto commit;
}
/*