We need to be able to iterate over all caps on a session with a
possibly slow callback on each cap. To allow this, we used to
prevent cap reordering while we were iterating. However, we were
not safe from races with removal: removing the 'next' cap would
make the next pointer from list_for_each_entry_safe be invalid,
and cause a lock up or similar badness.
Instead, we keep an iterator pointer in the session pointing to
the current cap. As before, we avoid reordering. For removal,
if the cap isn't the current cap we are iterating over, we are
fine. If it is, we clear cap->ci (to mark the cap as pending
removal) but leave it in the session list. In iterate_caps, we
can safely finish removal and get the next cap pointer.
While we're at it, clean up put_cap to not take a cap reservation
context, as it was never used.
Signed-off-by: Sage Weil <sage@newdream.net>
Use a global counter for the minimum number of allocated caps instead of
hard coding a check against readdir_max. This takes into account multiple
client instances, and avoids examining the superblock mount options when a
cap is dropped.
Signed-off-by: Sage Weil <sage@newdream.net>
We were invalidating mapping pages when dropping FILE_CACHE in
__send_cap(). But ceph_check_caps attempts to invalidate already, and
also checks for success, so we should never get to this point.
Signed-off-by: Sage Weil <sage@newdream.net>
Try to invalidate pages in ceph_check_caps() if FILE_CACHE is being
revoked. If we fail, queue an immediate async invalidate if FILE_CACHE
is being revoked. (If it's not being revoked, we just queue the caps
for later evaluation later, as per the old behavior.)
Signed-off-by: Sage Weil <sage@newdream.net>
Many (most?) message types include a transaction id. By including it in
the fixed size header, we always have it available even when we are unable
to allocate memory for the (larger, variable sized) message body. This
will allow us to error out the appropriate request instead of (silently)
dropping the reply.
Signed-off-by: Sage Weil <sage@newdream.net>
Avoid confusing iterate_session_caps(), flag the session while we are
iterating so that __touch_cap does not rearrange items on the list.
All other modifiers of session->s_caps do so under the protection of
s_mutex.
Signed-off-by: Sage Weil <sage@newdream.net>
We occasionally want to make a best-effort attempt to invalidate cache
pages without fear of blocking. If this fails, we fall back to an async
invalidate in another thread.
Use invalidate_mapping_pages instead of invalidate_inode_page2, as that
will skip locked pages, and not deadlock.
Signed-off-by: Sage Weil <sage@newdream.net>
We don't get an explicit affirmative confirmation that our caps reconnect,
nor do we necessarily want to pay that cost. So, take all this code out
for now.
Signed-off-by: Sage Weil <sage@newdream.net>
We were using the cap_gen to track both stale caps (caps that timed out
due to temporarily losing touch with the mds) and dead caps that did not
reconnect after an MDS failure. Introduce a recon_gen counter to track
reconnections to restarted MDSs and kill dead caps based on that instead.
Rename gen to cap_gen while we're at it to make it more clear which is
which.
Signed-off-by: Sage Weil <sage@newdream.net>
This simplifies much of the error handling during mount. It also means
that we have the mount args before client creation, and we can initialize
based on those options.
Signed-off-by: Sage Weil <sage@newdream.net>
Previously we were flushing dirty caps by passing an extra flag
when traversing the delayed caps list. Besides being a bit ugly,
that can also miss caps that are dirty but didn't result in a
cap requeue: notably, mark_caps_dirty().
Separate the flushing into a separate helper, and traverse the
cap_dirty list.
This also brings i_dirty_item in line with i_dirty_caps: we are
on the list IFF caps != 0. We carry an inode ref IFF
dirty_caps|flushing_caps != 0.
Lose the unused return value from __ceph_mark_caps_dirty().
Signed-off-by: Sage Weil <sage@newdream.net>
The Ceph metadata servers control client access to inode metadata and
file data by issuing capabilities, granting clients permission to read
and/or write both inode field and file data to OSDs (storage nodes).
Each capability consists of a set of bits indicating which operations
are allowed.
If the client holds a *_SHARED cap, the client has a coherent value
that can be safely read from the cached inode.
In the case of a *_EXCL (exclusive) or FILE_WR capabilities, the client
is allowed to change inode attributes (e.g., file size, mtime), note
its dirty state in the ceph_cap, and asynchronously flush that
metadata change to the MDS.
In the event of a conflicting operation (perhaps by another client),
the MDS will revoke the conflicting client capabilities.
In order for a client to cache an inode, it must hold a capability
with at least one MDS server. When inodes are released, release
notifications are batched and periodically sent en masse to the MDS
cluster to release server state.
Signed-off-by: Sage Weil <sage@newdream.net>
Sage Weil