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| author | Jeff Layton <jlayton@kernel.org> | 2019-11-13 09:10:27 -0500 |
|---|---|---|
| committer | Ilya Dryomov <idryomov@gmail.com> | 2019-11-14 18:44:51 +0100 |
| commit | a81bc3102b4ffb885f34855d0133f862f915ab13 (patch) | |
| tree | 5ce3d7f6ddc3c2b9ffbe43736f18115c9bc29948 /fs | |
| parent | 31f4f5b495a62c9a8b15b1c3581acd5efeb9af8c (diff) | |
| download | linux-a81bc3102b4ffb885f34855d0133f862f915ab13.tar.bz2 | |
ceph: take the inode lock before acquiring cap refs
Most of the time, we (or the vfs layer) takes the inode_lock and then
acquires caps, but ceph_read_iter does the opposite, and that can lead
to a deadlock.
When there are multiple clients treading over the same data, we can end
up in a situation where a reader takes caps and then tries to acquire
the inode_lock. Another task holds the inode_lock and issues a request
to the MDS which needs to revoke the caps, but that can't happen until
the inode_lock is unwedged.
Fix this by having ceph_read_iter take the inode_lock earlier, before
attempting to acquire caps.
Fixes: 321fe13c9398 ("ceph: add buffered/direct exclusionary locking for reads and writes")
Link: https://tracker.ceph.com/issues/36348
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/ceph/file.c | 25 |
1 files changed, 18 insertions, 7 deletions
diff --git a/fs/ceph/file.c b/fs/ceph/file.c index bd77adb64bfd..06efeaff3b57 100644 --- a/fs/ceph/file.c +++ b/fs/ceph/file.c @@ -1264,14 +1264,24 @@ again: dout("aio_read %p %llx.%llx %llu~%u trying to get caps on %p\n", inode, ceph_vinop(inode), iocb->ki_pos, (unsigned)len, inode); + if (iocb->ki_flags & IOCB_DIRECT) + ceph_start_io_direct(inode); + else + ceph_start_io_read(inode); + if (fi->fmode & CEPH_FILE_MODE_LAZY) want = CEPH_CAP_FILE_CACHE | CEPH_CAP_FILE_LAZYIO; else want = CEPH_CAP_FILE_CACHE; ret = ceph_get_caps(filp, CEPH_CAP_FILE_RD, want, -1, &got, &pinned_page); - if (ret < 0) + if (ret < 0) { + if (iocb->ki_flags & IOCB_DIRECT) + ceph_end_io_direct(inode); + else + ceph_end_io_read(inode); return ret; + } if ((got & (CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO)) == 0 || (iocb->ki_flags & IOCB_DIRECT) || @@ -1283,16 +1293,12 @@ again: if (ci->i_inline_version == CEPH_INLINE_NONE) { if (!retry_op && (iocb->ki_flags & IOCB_DIRECT)) { - ceph_start_io_direct(inode); ret = ceph_direct_read_write(iocb, to, NULL, NULL); - ceph_end_io_direct(inode); if (ret >= 0 && ret < len) retry_op = CHECK_EOF; } else { - ceph_start_io_read(inode); ret = ceph_sync_read(iocb, to, &retry_op); - ceph_end_io_read(inode); } } else { retry_op = READ_INLINE; @@ -1303,11 +1309,10 @@ again: inode, ceph_vinop(inode), iocb->ki_pos, (unsigned)len, ceph_cap_string(got)); ceph_add_rw_context(fi, &rw_ctx); - ceph_start_io_read(inode); ret = generic_file_read_iter(iocb, to); - ceph_end_io_read(inode); ceph_del_rw_context(fi, &rw_ctx); } + dout("aio_read %p %llx.%llx dropping cap refs on %s = %d\n", inode, ceph_vinop(inode), ceph_cap_string(got), (int)ret); if (pinned_page) { @@ -1315,6 +1320,12 @@ again: pinned_page = NULL; } ceph_put_cap_refs(ci, got); + + if (iocb->ki_flags & IOCB_DIRECT) + ceph_end_io_direct(inode); + else + ceph_end_io_read(inode); + if (retry_op > HAVE_RETRIED && ret >= 0) { int statret; struct page *page = NULL; |