NFSv4.1: Don't drop the pnfs_layout_hdr after a layoutget failure

We want to cache the pnfs_layout_hdr after a layoutget or i/o
failure so that pnfs_update_layout() can find it and know when
it is time to retry.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/pnfs.c

@@ -247,10 +247,28 @@ pnfs_iomode_to_fail_bit(u32 iomode)
 }
 
 static void
-pnfs_layout_io_set_failed(struct pnfs_layout_hdr *lo, u32 iomode)
+pnfs_layout_set_fail_bit(struct pnfs_layout_hdr *lo, int fail_bit)
 {
 	lo->plh_retry_timestamp = jiffies;
-	set_bit(pnfs_iomode_to_fail_bit(iomode), &lo->plh_flags);
+	if (test_and_set_bit(fail_bit, &lo->plh_flags))
+		atomic_inc(&lo->plh_refcount);
+}
+
+static void
+pnfs_layout_clear_fail_bit(struct pnfs_layout_hdr *lo, int fail_bit)
+{
+	if (test_and_clear_bit(fail_bit, &lo->plh_flags))
+		atomic_dec(&lo->plh_refcount);
+}
+
+static void
+pnfs_layout_io_set_failed(struct pnfs_layout_hdr *lo, u32 iomode)
+{
+	struct inode *inode = lo->plh_inode;
+
+	spin_lock(&inode->i_lock);
+	pnfs_layout_set_fail_bit(lo, pnfs_iomode_to_fail_bit(iomode));
+	spin_unlock(&inode->i_lock);
 	dprintk("%s Setting layout IOMODE_%s fail bit\n", __func__,
 			iomode == IOMODE_RW ?  "RW" : "READ");
 }
@@ -259,14 +277,15 @@ static bool
 pnfs_layout_io_test_failed(struct pnfs_layout_hdr *lo, u32 iomode)
 {
 	unsigned long start, end;
-	if (test_bit(pnfs_iomode_to_fail_bit(iomode), &lo->plh_flags) == 0)
+	int fail_bit = pnfs_iomode_to_fail_bit(iomode);
+
+	if (test_bit(fail_bit, &lo->plh_flags) == 0)
 		return false;
 	end = jiffies;
 	start = end - PNFS_LAYOUTGET_RETRY_TIMEOUT;
 	if (!time_in_range(lo->plh_retry_timestamp, start, end)) {
 		/* It is time to retry the failed layoutgets */
-		clear_bit(NFS_LAYOUT_RW_FAILED, &lo->plh_flags);
-		clear_bit(NFS_LAYOUT_RO_FAILED, &lo->plh_flags);
+		pnfs_layout_clear_fail_bit(lo, fail_bit);
 		return false;
 	}
 	return true;
@@ -493,9 +512,14 @@ pnfs_destroy_layout(struct nfs_inode *nfsi)
 	if (lo) {
 		lo->plh_block_lgets++; /* permanently block new LAYOUTGETs */
 		pnfs_mark_matching_lsegs_invalid(lo, &tmp_list, NULL);
-	}
+		pnfs_get_layout_hdr(lo);
+		pnfs_layout_clear_fail_bit(lo, NFS_LAYOUT_RO_FAILED);
+		pnfs_layout_clear_fail_bit(lo, NFS_LAYOUT_RW_FAILED);
 		spin_unlock(&nfsi->vfs_inode.i_lock);
 		pnfs_free_lseg_list(&tmp_list);
+		pnfs_put_layout_hdr(lo);
+	} else
+		spin_unlock(&nfsi->vfs_inode.i_lock);
 }
 EXPORT_SYMBOL_GPL(pnfs_destroy_layout);