kernel/git/stable/linux.git/fs/ceph/caps.c, branch linux-5.9.y

ceph: check session state after bumping session->s_seq

2020-11-18T18:22:07+00:00

[ Upstream commit 62575e270f661aba64778cbc5f354511cf9abb21 ] Some messages sent by the MDS entail a session sequence number increment, and the MDS will drop certain types of requests on the floor when the sequence numbers don't match. In particular, a REQUEST_CLOSE message can cross with one of the sequence morphing messages from the MDS which can cause the client to stall, waiting for a response that will never come. Originally, this meant an up to 5s delay before the recurring workqueue job kicked in and resent the request, but a recent change made it so that the client would never resend, causing a 60s stall unmounting and sometimes a blockisting event. Add a new helper for incrementing the session sequence and then testing to see whether a REQUEST_CLOSE needs to be resent, and move the handling of CEPH_MDS_SESSION_CLOSING into that function. Change all of the bare sequence counter increments to use the new helper. Reorganize check_session_state with a switch statement. It should no longer be called when the session is CLOSING, so throw a warning if it ever is (but still handle that case sanely). [ idryomov: whitespace, pr_err() call fixup ] URL: https://tracker.ceph.com/issues/47563 Fixes: fa9967734227 ("ceph: fix potential mdsc use-after-free crash") Reported-by: Patrick Donnelly Signed-off-by: Jeff Layton Reviewed-by: Ilya Dryomov Reviewed-by: Xiubo Li Signed-off-by: Ilya Dryomov Signed-off-by: Sasha Levin

ceph: fix inode number handling on arches with 32-bit ino_t

2020-08-24T15:25:26+00:00

Tuan and Ulrich mentioned that they were hitting a problem on s390x, which has a 32-bit ino_t value, even though it's a 64-bit arch (for historical reasons). I think the current handling of inode numbers in the ceph driver is wrong. It tries to use 32-bit inode numbers on 32-bit arches, but that's actually not a problem. 32-bit arches can deal with 64-bit inode numbers just fine when userland code is compiled with LFS support (the common case these days). What we really want to do is just use 64-bit numbers everywhere, unless someone has mounted with the ino32 mount option. In that case, we want to ensure that we hash the inode number down to something that will fit in 32 bits before presenting the value to userland. Add new helper functions that do this, and only do the conversion before presenting these values to userland in getattr and readdir. The inode table hashvalue is changed to just cast the inode number to unsigned long, as low-order bits are the most likely to vary anyway. While it's not strictly required, we do want to put something in inode->i_ino. Instead of basing it on BITS_PER_LONG, however, base it on the size of the ino_t type. NOTE: This is a user-visible change on 32-bit arches: 1/ inode numbers will be seen to have changed between kernel versions. 32-bit arches will see large inode numbers now instead of the hashed ones they saw before. 2/ any really old software not built with LFS support may start failing stat() calls with -EOVERFLOW on inode numbers >2^32. Nothing much we can do about these, but hopefully the intersection of people running such code on ceph will be very small. The workaround for both problems is to mount with "-o ino32". [ idryomov: changelog tweak ] URL: https://tracker.ceph.com/issues/46828 Reported-by: Ulrich Weigand Reported-and-Tested-by: Tuan Hoang1 Signed-off-by: Jeff Layton Reviewed-by: "Yan, Zheng" Signed-off-by: Ilya Dryomov

ceph: clean up and optimize ceph_check_delayed_caps()

2020-08-03T09:05:21+00:00

Make this loop look a bit more sane. Also optimize away the spinlock release/reacquire if we can't get an inode reference. Signed-off-by: Jeff Layton Reviewed-by: Xiubo Li Signed-off-by: Ilya Dryomov

ceph: add global total_caps to count the mdsc's total caps number

2020-08-03T09:05:15+00:00

This will help to reduce using the global mdsc->mutex lock in many places. Signed-off-by: Xiubo Li Reviewed-by: Jeff Layton Signed-off-by: Ilya Dryomov

ceph: skip checking caps when session reconnecting and releasing reqs

2020-06-01T11:22:53+00:00

It make no sense to check the caps when reconnecting to mds. And for the async dirop caps, they will be put by its _cb() function, so when releasing the requests, it will make no sense too. URL: https://tracker.ceph.com/issues/45635 Signed-off-by: Xiubo Li Reviewed-by: "Yan, Zheng" Signed-off-by: Ilya Dryomov

ceph: ceph_kick_flushing_caps needs the s_mutex

2020-06-01T11:22:53+00:00

The mdsc->cap_dirty_lock is not held while walking the list in ceph_kick_flushing_caps, which is not safe. ceph_early_kick_flushing_caps does something similar, but the s_mutex is held while it's called and I think that guards against changes to the list. Ensure we hold the s_mutex when calling ceph_kick_flushing_caps, and add some clarifying comments. Signed-off-by: Jeff Layton Reviewed-by: "Yan, Zheng" Signed-off-by: Ilya Dryomov

ceph: request expedited service on session's last cap flush

2020-06-01T11:22:52+00:00

When flushing a lot of caps to the MDS's at once (e.g. for syncfs), we can end up waiting a substantial amount of time for MDS replies, due to the fact that it may delay some of them so that it can batch them up together in a single journal transaction. This can lead to stalls when calling sync or syncfs. What we'd really like to do is request expedited service on the _last_ cap we're flushing back to the server. If the CHECK_CAPS_FLUSH flag is set on the request and the current inode was the last one on the session->s_cap_dirty list, then mark the request with CEPH_CLIENT_CAPS_SYNC. Note that this heuristic is not perfect. New inodes can race onto the list after we've started flushing, but it does seem to fix some common use cases. URL: https://tracker.ceph.com/issues/44744 Reported-by: Jan Fajerski Signed-off-by: Jeff Layton Reviewed-by: "Yan, Zheng" Signed-off-by: Ilya Dryomov

ceph: convert mdsc->cap_dirty to a per-session list

2020-06-01T11:22:52+00:00

This is a per-sb list now, but that makes it difficult to tell when the cap is the last dirty one associated with the session. Switch this to be a per-session list, but continue using the mdsc->cap_dirty_lock to protect the lists. This list is only ever walked in ceph_flush_dirty_caps, so change that to walk the sessions array and then flush the caps for inodes on each session's list. If the auth cap ever changes while the inode has dirty caps, then move the inode to the appropriate session for the new auth_cap. Also, ensure that we never remove an auth cap while the inode is still on the s_cap_dirty list. Signed-off-by: Jeff Layton Reviewed-by: "Yan, Zheng" Signed-off-by: Ilya Dryomov

ceph: reset i_requested_max_size if file write is not wanted

2020-06-01T11:22:52+00:00

write can stuck at waiting for larger max_size in following sequence of events: - client opens a file and writes to position 'A' (larger than unit of max size increment) - client closes the file handle and updates wanted caps (not wanting file write caps) - client opens and truncates the file, writes to position 'A' again. At the 1st event, client set inode's requested_max_size to 'A'. At the 2nd event, mds removes client's writable range, but client does not reset requested_max_size. At the 3rd event, client does not request max size because requested_max_size is already larger than 'A'. Signed-off-by: "Yan, Zheng" Reviewed-by: Jeff Layton Signed-off-by: Ilya Dryomov

ceph: fix potential race in ceph_check_caps

2020-06-01T11:22:52+00:00

Nothing ensures that session will still be valid by the time we dereference the pointer. Take and put a reference. In principle, we should always be able to get a reference here, but throw a warning if that's ever not the case. Signed-off-by: Jeff Layton Signed-off-by: Ilya Dryomov