diff mbox series

[RFC] ceph: try to prevent exceeding the MDS maximum xattr size

Message ID 20220520115426.438-1-lhenriques@suse.de
State New
Headers show
Series [RFC] ceph: try to prevent exceeding the MDS maximum xattr size | expand

Commit Message

Luis Henriques May 20, 2022, 11:54 a.m. UTC 
The MDS tries to enforce a limit on the total key/values in extended
attributes.  However, this limit is enforced only if doing a synchronous
operation (MDS_OP_SETXATTR) -- if we're buffering the xattrs, the MDS
doesn't have a chance to enforce these limits.

This patch forces the usage of the synchronous operation if xattrs size hits
the maximum size that is set on the MDS by default (64k).

While there, fix a dout() that would trigger a printk warning:

[   98.718078] ------------[ cut here ]------------
[   98.719012] precision 65536 too large
[   98.719039] WARNING: CPU: 1 PID: 3755 at lib/vsprintf.c:2703 vsnprintf+0x5e3/0x600
...

URL: https://tracker.ceph.com/issues/55725
Signed-off-by: Luís Henriques <lhenriques@suse.de>
---
 fs/ceph/xattr.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)
diff mbox series

Patch

diff --git a/fs/ceph/xattr.c b/fs/ceph/xattr.c
index afec84088471..09751a5f028c 100644
--- a/fs/ceph/xattr.c
+++ b/fs/ceph/xattr.c
@@ -15,6 +15,12 @@ 
 #define XATTR_CEPH_PREFIX "ceph."
 #define XATTR_CEPH_PREFIX_LEN (sizeof (XATTR_CEPH_PREFIX) - 1)
 
+/*
+ * Maximum size of xattrs the MDS can handle per inode by default.  This
+ * includes the attribute name and 4+4 bytes for the key/value sizes.
+ */
+#define MDS_MAX_XATTR_PAIRS_SIZE (1<<16) /* 64K */
+
 static int __remove_xattr(struct ceph_inode_info *ci,
 			  struct ceph_inode_xattr *xattr);
 
@@ -1078,7 +1084,7 @@  static int ceph_sync_setxattr(struct inode *inode, const char *name,
 			flags |= CEPH_XATTR_REMOVE;
 	}
 
-	dout("setxattr value=%.*s\n", (int)size, value);
+	dout("setxattr value size: ld\n", size);
 
 	/* do request */
 	req = ceph_mdsc_create_request(mdsc, op, USE_AUTH_MDS);
@@ -1176,8 +1182,13 @@  int __ceph_setxattr(struct inode *inode, const char *name,
 	spin_lock(&ci->i_ceph_lock);
 retry:
 	issued = __ceph_caps_issued(ci, NULL);
-	if (ci->i_xattrs.version == 0 || !(issued & CEPH_CAP_XATTR_EXCL))
+	required_blob_size = __get_required_blob_size(ci, name_len, val_len);
+	if ((ci->i_xattrs.version == 0) || !(issued & CEPH_CAP_XATTR_EXCL) ||
+	    (required_blob_size >= MDS_MAX_XATTR_PAIRS_SIZE)) {
+		dout("%s do sync setxattr: version: %llu blob size: %d\n",
+		     __func__, ci->i_xattrs.version, required_blob_size);
 		goto do_sync;
+	}
 
 	if (!lock_snap_rwsem && !ci->i_head_snapc) {
 		lock_snap_rwsem = true;
@@ -1193,8 +1204,6 @@  int __ceph_setxattr(struct inode *inode, const char *name,
 	     ceph_cap_string(issued));
 	__build_xattrs(inode);
 
-	required_blob_size = __get_required_blob_size(ci, name_len, val_len);
-
 	if (!ci->i_xattrs.prealloc_blob ||
 	    required_blob_size > ci->i_xattrs.prealloc_blob->alloc_len) {
 		struct ceph_buffer *blob;