On 6/3/22 7:52 PM, Luís Henriques wrote:
Xiubo Li <xiubli@xxxxxxxxxx> writes:On 6/2/22 10:36 PM, Luís Henriques wrote: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 adds support for decoding the xattrs maximum size setting that is distributed in the mdsmap. Then, when setting an xattr, the kernel client will revert to do a synchronous operation if that maximum size is exceeded. 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@xxxxxxx> --- fs/ceph/mdsmap.c | 28 ++++++++++++++++++++++++---- fs/ceph/xattr.c | 12 ++++++++---- include/linux/ceph/mdsmap.h | 1 + 3 files changed, 33 insertions(+), 8 deletions(-) * Changes since v3 As per Xiubo review: - Always force a (sync) SETXATTR Op when connecting to an old cluster - use '>' instead of '>=' Also fixed the warning detected by 0day. * Changes since v2 Well, a lot has changed since v2! Now the xattr max value setting is obtained through the mdsmap, which needs to be decoded, and the feature that was used in the previous revision was dropped. The drawback is that the MDS isn't unable to know in advance if a client is aware of this xattr max value. * Changes since v1 Added support for new feature bit to get the MDS max_xattr_pairs_size setting. Also note that this patch relies on a patch that hasn't been merged yet ("ceph: use correct index when encoding client supported features"), otherwise the new feature bit won't be correctly encoded. diff --git a/fs/ceph/mdsmap.c b/fs/ceph/mdsmap.c index 30387733765d..c6ce83a48175 100644 --- a/fs/ceph/mdsmap.c +++ b/fs/ceph/mdsmap.c @@ -13,6 +13,12 @@ #include "super.h" +/* + * 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_SIZE (1<<16) /* 64K */This macro makes no sense anymore, right ?Ah, yeah. That's still leftovers from the previous version.I will merge this patch by removing this then.Thanks! Also... maybe you could also fix the (embarrassing) issue detected by 0day that I _tried_ to fix but failed (see below).-- Xiubo+ #define CEPH_MDS_IS_READY(i, ignore_laggy) \ (m->m_info[i].state > 0 && ignore_laggy ? true : !m->m_info[i].laggy) @@ -352,12 +358,10 @@ struct ceph_mdsmap *ceph_mdsmap_decode(void **p, void *end, bool msgr2) __decode_and_drop_type(p, end, u8, bad_ext); } if (mdsmap_ev >= 8) { - u32 name_len; /* enabled */ ceph_decode_8_safe(p, end, m->m_enabled, bad_ext); - ceph_decode_32_safe(p, end, name_len, bad_ext); - ceph_decode_need(p, end, name_len, bad_ext); - *p += name_len; + /* fs_name */ + ceph_decode_skip_string(p, end, bad_ext); } /* damaged */ if (mdsmap_ev >= 9) { @@ -370,6 +374,22 @@ struct ceph_mdsmap *ceph_mdsmap_decode(void **p, void *end, bool msgr2) } else { m->m_damaged = false; } + if (mdsmap_ev >= 17) { + /* balancer */ + ceph_decode_skip_string(p, end, bad_ext); + /* standby_count_wanted */ + ceph_decode_skip_32(p, end, bad_ext); + /* old_max_mds */ + ceph_decode_skip_32(p, end, bad_ext); + /* min_compat_client */ + ceph_decode_skip_8(p, end, bad_ext); + /* required_client_features */ + ceph_decode_skip_set(p, end, 64, bad_ext); + ceph_decode_64_safe(p, end, m->m_max_xattr_size, bad_ext); + } else { + /* This forces the usage of the (sync) SETXATTR Op */ + m->m_max_xattr_size = 0; + } bad_ext: dout("mdsmap_decode m_enabled: %d, m_damaged: %d, m_num_laggy: %d\n", !!m->m_enabled, !!m->m_damaged, m->m_num_laggy); diff --git a/fs/ceph/xattr.c b/fs/ceph/xattr.c index 8c2dc2c762a4..1be415e9220b 100644 --- a/fs/ceph/xattr.c +++ b/fs/ceph/xattr.c @@ -1086,7 +1086,7 @@ 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: %lu\n", size);This should be "%zu" and not "%lu". I'm OK sending v5 to fix these 2 issues if you prefer.
Sure, please send a v5 for it.
[ And then there's also the MDS-side which hasn't been merged yet. But this patch is probably worth in itself as it will change the client behavior to do the sync operation. ]
It's okay, this will fix this issue when we are connecting to old cephs, and we could force to do the sync request always.
No need to wait the ceph PR. -- Xiubo
Cheers,
