Remove zpl_revalidate: fix snapshot rollback

Open files, which aren't present in the snapshot, which is being
roll-backed to, need to disappear from the visible VFS image of
the dataset.

Kernel provides d_drop function to drop invalid entry from
the dcache, but inode can be referenced by dentry multiple dentries.

The introduced zpl_d_drop_aliases function walks and invalidates
all aliases of an inode.

Reviewed-by: Ryan Moeller <[email protected]>
Reviewed-by: Alexander Motin <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Pavel Snajdr <[email protected]>
Closes #9600
Closes #14070

4 files changed, 1 insertions, 48 deletions

diff --git a/module/os/linux/zfs/zfs_ctldir.c b/module/os/linux/zfs/zfs_ctldir.c
index d33188f38..c45644a69 100644
--- a/module/os/linux/zfs/zfs_ctldir.c
+++ b/module/os/linux/zfs/zfs_ctldir.c
@@ -470,7 +470,6 @@ zfsctl_inode_alloc(zfsvfs_t *zfsvfs, uint64_t id,
 	zp->z_is_sa = B_FALSE;
 	zp->z_is_mapped = B_FALSE;
 	zp->z_is_ctldir = B_TRUE;
-	zp->z_is_stale = B_FALSE;
 	zp->z_sa_hdl = NULL;
 	zp->z_blksz = 0;
 	zp->z_seq = 0;
diff --git a/module/os/linux/zfs/zfs_vfsops.c b/module/os/linux/zfs/zfs_vfsops.c
index 2e1b9ba5b..da897f120 100644
--- a/module/os/linux/zfs/zfs_vfsops.c
+++ b/module/os/linux/zfs/zfs_vfsops.c
@@ -1500,7 +1500,6 @@ zfs_domount(struct super_block *sb, zfs_mnt_t *zm, int silent)
 	sb->s_op = &zpl_super_operations;
 	sb->s_xattr = zpl_xattr_handlers;
 	sb->s_export_op = &zpl_export_operations;
-	sb->s_d_op = &zpl_dentry_operations;
 
 	/* Set features for file system. */
 	zfs_set_fuid_feature(zfsvfs);
@@ -1859,8 +1858,8 @@ zfs_resume_fs(zfsvfs_t *zfsvfs, dsl_dataset_t *ds)
 	    zp = list_next(&zfsvfs->z_all_znodes, zp)) {
 		err2 = zfs_rezget(zp);
 		if (err2) {
+			zpl_d_drop_aliases(ZTOI(zp));
 			remove_inode_hash(ZTOI(zp));
-			zp->z_is_stale = B_TRUE;
 		}
 
 		/* see comment in zfs_suspend_fs() */
diff --git a/module/os/linux/zfs/zfs_znode.c b/module/os/linux/zfs/zfs_znode.c
index cd80049df..ba2375387 100644
--- a/module/os/linux/zfs/zfs_znode.c
+++ b/module/os/linux/zfs/zfs_znode.c
@@ -544,7 +544,6 @@ zfs_znode_alloc(zfsvfs_t *zfsvfs, dmu_buf_t *db, int blksz,
 	zp->z_atime_dirty = B_FALSE;
 	zp->z_is_mapped = B_FALSE;
 	zp->z_is_ctldir = B_FALSE;
-	zp->z_is_stale = B_FALSE;
 	zp->z_suspended = B_FALSE;
 	zp->z_sa_hdl = NULL;
 	zp->z_mapcnt = 0;
diff --git a/module/os/linux/zfs/zpl_inode.c b/module/os/linux/zfs/zpl_inode.c
index 4f79265a0..a0615af8d 100644
--- a/module/os/linux/zfs/zpl_inode.c
+++ b/module/os/linux/zfs/zpl_inode.c
@@ -698,46 +698,6 @@ out:
 	return (error);
 }
 
-static int
-#ifdef HAVE_D_REVALIDATE_NAMEIDATA
-zpl_revalidate(struct dentry *dentry, struct nameidata *nd)
-{
-	unsigned int flags = (nd ? nd->flags : 0);
-#else
-zpl_revalidate(struct dentry *dentry, unsigned int flags)
-{
-#endif /* HAVE_D_REVALIDATE_NAMEIDATA */
-	/* CSTYLED */
-	zfsvfs_t *zfsvfs = dentry->d_sb->s_fs_info;
-	int error;
-
-	if (flags & LOOKUP_RCU)
-		return (-ECHILD);
-
-	/*
-	 * After a rollback negative dentries created before the rollback
-	 * time must be invalidated.  Otherwise they can obscure files which
-	 * are only present in the rolled back dataset.
-	 */
-	if (dentry->d_inode == NULL) {
-		spin_lock(&dentry->d_lock);
-		error = time_before(dentry->d_time, zfsvfs->z_rollback_time);
-		spin_unlock(&dentry->d_lock);
-
-		if (error)
-			return (0);
-	}
-
-	/*
-	 * The dentry may reference a stale inode if a mounted file system
-	 * was rolled back to a point in time where the object didn't exist.
-	 */
-	if (dentry->d_inode && ITOZ(dentry->d_inode)->z_is_stale)
-		return (0);
-
-	return (1);
-}
-
 const struct inode_operations zpl_inode_operations = {
 	.setattr	= zpl_setattr,
 	.getattr	= zpl_getattr,
@@ -826,7 +786,3 @@ const struct inode_operations zpl_special_inode_operations = {
 	.get_acl	= zpl_get_acl,
 #endif /* CONFIG_FS_POSIX_ACL */
 };
-
-dentry_operations_t zpl_dentry_operations = {
-	.d_revalidate	= zpl_revalidate,
-};