[PATCH] ceph: increase the offset when fail to decode dentry names

[xiubli@xxxxxxxxxx]

From: Xiubo Li <xiubli@xxxxxxxxxx>

------------[ cut here ]------------
kernel BUG at fs/ceph/dir.c:537!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN NOPTI
CPU: 16 PID: 21641 Comm: ls Tainted: G            E     5.17.0-rc2+ #92
Hardware name: Red Hat RHEV Hypervisor, BIOS 1.11.0-2.el7 04/01/2014

The corresponding code in ceph_readdir() is:

	BUG_ON(rde->offset < ctx->pos);

Signed-off-by: Xiubo Li <xiubli@xxxxxxxxxx>
---
 fs/ceph/dir.c   | 13 +++++++------
 fs/ceph/inode.c |  3 ++-
 2 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
index a449f4a07c07..f28eb568e0e2 100644
--- a/fs/ceph/dir.c
+++ b/fs/ceph/dir.c
@@ -534,6 +534,13 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx)
 					    .ctext_len	= rde->altname_len };
 		u32 olen = oname.len;
 
+		err = ceph_fname_to_usr(&fname, &tname, &oname, NULL);
+		if (err) {
+			pr_warn("Unable to decode %.*s. Skipping it.\n", rde->name_len, rde->name);
+			ctx->pos++;
+			continue;
+		}
+
 		BUG_ON(rde->offset < ctx->pos);
 		BUG_ON(!rde->inode.in);
 
@@ -542,12 +549,6 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx)
 		     i, rinfo->dir_nr, ctx->pos,
 		     rde->name_len, rde->name, &rde->inode.in);
 
-		err = ceph_fname_to_usr(&fname, &tname, &oname, NULL);
-		if (err) {
-			dout("Unable to decode %.*s. Skipping it.\n", rde->name_len, rde->name);
-			continue;
-		}
-
 		if (!dir_emit(ctx, oname.name, oname.len,
 			      ceph_present_ino(inode->i_sb, le64_to_cpu(rde->inode.in->ino)),
 			      le32_to_cpu(rde->inode.in->mode) >> 12)) {
diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index 8b0832271fdf..b1552e6a6f0e 100644
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -1898,7 +1898,8 @@ int ceph_readdir_prepopulate(struct ceph_mds_request *req,
 
 		err = ceph_fname_to_usr(&fname, &tname, &oname, &is_nokey);
 		if (err) {
-			dout("Unable to decode %.*s. Skipping it.", rde->name_len, rde->name);
+			fpos_offset++;
+			pr_warn("Unable to decode %.*s. Skipping it.", rde->name_len, rde->name);
 			continue;
 		}
 
-- 
2.27.0