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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_dir.c
+70 -25
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@@ -926,6 +926,74 @@ zfs_dropname(zfs_dirlock_t *dl, znode_t *zp, znode_t *dzp, dmu_tx_t *tx,
return (error);
}
static int
zfs_drop_nlink_locked(znode_t *zp, dmu_tx_t *tx, boolean_t *unlinkedp)
{
zfsvfs_t *zfsvfs = ZTOZSB(zp);
int zp_is_dir = S_ISDIR(ZTOI(zp)->i_mode);
boolean_t unlinked = B_FALSE;
sa_bulk_attr_t bulk[3];
uint64_t mtime[2], ctime[2];
uint64_t links;
int count = 0;
int error;
if (zp_is_dir && !zfs_dirempty(zp))
return (SET_ERROR(ENOTEMPTY));
if (ZTOI(zp)->i_nlink <= zp_is_dir) {
zfs_panic_recover("zfs: link count on %lu is %u, "
"should be at least %u", zp->z_id,
(int)ZTOI(zp)->i_nlink, zp_is_dir + 1);
set_nlink(ZTOI(zp), zp_is_dir + 1);
}
drop_nlink(ZTOI(zp));
if (ZTOI(zp)->i_nlink == zp_is_dir) {
zp->z_unlinked = B_TRUE;
clear_nlink(ZTOI(zp));
unlinked = B_TRUE;
} else {
SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_CTIME(zfsvfs),
NULL, &ctime, sizeof (ctime));
SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_FLAGS(zfsvfs),
NULL, &zp->z_pflags, sizeof (zp->z_pflags));
zfs_tstamp_update_setup(zp, STATE_CHANGED, mtime,
ctime);
}
links = ZTOI(zp)->i_nlink;
SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_LINKS(zfsvfs),
NULL, &links, sizeof (links));
error = sa_bulk_update(zp->z_sa_hdl, bulk, count, tx);
ASSERT3U(error, ==, 0);
if (unlinkedp != NULL)
*unlinkedp = unlinked;
else if (unlinked)
zfs_unlinked_add(zp, tx);
return (0);
}
/*
* Forcefully drop an nlink reference from (zp) and mark it for deletion if it
* was the last link. This *must* only be done to znodes which have already
* been zfs_link_destroy()'d with ZRENAMING. This is explicitly only used in
* the error path of zfs_rename(), where we have to correct the nlink count if
* we failed to link the target as well as failing to re-link the original
* znodes.
*/
int
zfs_drop_nlink(znode_t *zp, dmu_tx_t *tx, boolean_t *unlinkedp)
{
int error;
mutex_enter(&zp->z_lock);
error = zfs_drop_nlink_locked(zp, tx, unlinkedp);
mutex_exit(&zp->z_lock);
return (error);
}
/*
* Unlink zp from dl, and mark zp for deletion if this was the last link. Can
* fail if zp is a mount point (EBUSY) or a non-empty directory (ENOTEMPTY).
@@ -966,31 +1034,8 @@ zfs_link_destroy(zfs_dirlock_t *dl, znode_t *zp, dmu_tx_t *tx, int flag,
return (error);
}
if (ZTOI(zp)->i_nlink <= zp_is_dir) {
zfs_panic_recover("zfs: link count on %lu is %u, "
"should be at least %u", zp->z_id,
(int)ZTOI(zp)->i_nlink, zp_is_dir + 1);
set_nlink(ZTOI(zp), zp_is_dir + 1);
}
drop_nlink(ZTOI(zp));
if (ZTOI(zp)->i_nlink == zp_is_dir) {
zp->z_unlinked = B_TRUE;
clear_nlink(ZTOI(zp));
unlinked = B_TRUE;
} else {
SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_CTIME(zfsvfs),
NULL, &ctime, sizeof (ctime));
SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_FLAGS(zfsvfs),
NULL, &zp->z_pflags, sizeof (zp->z_pflags));
zfs_tstamp_update_setup(zp, STATE_CHANGED, mtime,
ctime);
}
links = ZTOI(zp)->i_nlink;
SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_LINKS(zfsvfs),
NULL, &links, sizeof (links));
error = sa_bulk_update(zp->z_sa_hdl, bulk, count, tx);
count = 0;
ASSERT(error == 0);
/* The only error is !zfs_dirempty() and we checked earlier. */
ASSERT3U(zfs_drop_nlink_locked(zp, tx, &unlinked), ==, 0);
mutex_exit(&zp->z_lock);
} else {
error = zfs_dropname(dl, zp, dzp, tx, flag);