Luís Henriques <[email protected]> writes:
> 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 <[email protected]>
> ---
> fs/ceph/xattr.c | 17 +++++++++++++----
> 1 file changed, 13 insertions(+), 4 deletions(-)
>
> 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);
Oops! Looks like someone ate a '%' char. Oh well, I won't bother sending
out a new version for now as this is an RFC and the MDS side is what
really needs fixing. In fact, the client-side may be something very
different from this RFC.
Cheers,
--
Luís
>
> /* 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;