[PATCH 5.17 0092/1126] cifs: do not skip link targets when an I/O fails

Greg Kroah-Hartman
2022-04-05T07:47:49Z

From: Paulo Alcantara <pc@cjr.nz>

commit 5d7e282541fc91b831a5c4477c5d72881c623df9 upstream.

When I/O fails in one of the currently connected DFS targets, retry it
from other targets as specified in MS-DFSC "3.1.5.2 I/O Operation to
+Target Fails with an Error Other Than STATUS_PATH_NOT_COVERED."

Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Cc: stable@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/cifs/connect.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)

--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -3473,6 +3473,9 @@ static int connect_dfs_target(struct mou
struct cifs_sb_info *cifs_sb = mnt_ctx->cifs_sb;
char *oldmnt = cifs_sb->ctx->mount_options;

+ cifs_dbg(FYI, "%s: full_path=%s ref_path=%s target=%s\n", __func__, full_path, ref_path,
+ dfs_cache_get_tgt_name(tit));
+
rc = dfs_cache_get_tgt_referral(ref_path, tit, &ref);
if (rc)
goto out;
@@ -3571,13 +3574,18 @@ static int __follow_dfs_link(struct moun
if (rc)
goto out;

- /* Try all dfs link targets */
+ /* Try all dfs link targets. If an I/O fails from currently connected DFS target with an
+ * error other than STATUS_PATH_NOT_COVERED (-EREMOTE), then retry it from other targets as
+ * specified in MS-DFSC "3.1.5.2 I/O Operation to Target Fails with an Error Other Than
+ * STATUS_PATH_NOT_COVERED."
+ */
for (rc = -ENOENT, tit = dfs_cache_get_tgt_iterator(&tl);
tit; tit = dfs_cache_get_next_tgt(&tl, tit)) {
rc = connect_dfs_target(mnt_ctx, full_path, mnt_ctx->leaf_fullpath + 1, tit);
if (!rc) {
rc = is_path_remote(mnt_ctx);
- break;
+ if (!rc || rc == -EREMOTE)
+ break;
}
}

@@ -3651,7 +3659,7 @@ int cifs_mount(struct cifs_sb_info *cifs
goto error;

rc = is_path_remote(&mnt_ctx);
- if (rc == -EREMOTE)
+ if (rc)
rc = follow_dfs_link(&mnt_ctx);
if (rc)
goto error;