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afs: Fix interruption of operations

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The afs filesystem driver allows unstarted operations to be cancelled by
signal, but most of these can easily be restarted (mkdir for example).  The
primary culprits for reproducing this are those applications that use
SIGALRM to display a progress counter.

File lock-extension operation is marked uninterruptible as we have a
limited time in which to do it, and the release op is marked
uninterruptible also as if we fail to unlock a file, we'll have to wait 20
mins before anyone can lock it again.

The store operation logs a warning if it gets interruption, e.g.:

	kAFS: Unexpected error from FS.StoreData -4

because it's run from the background - but it can also be run from
fdatasync()-type things.  However, store options aren't marked
interruptible at the moment.

Fix this in the following ways:

 (1) Mark store operations as uninterruptible.  It might make sense to
     relax this for certain situations, but I'm not sure how to make sure
     that background store ops aren't affected by signals to foreground
     processes that happen to trigger them.

 (2) In afs_get_io_locks(), where we're getting the serialisation lock for
     talking to the fileserver, return ERESTARTSYS rather than EINTR
     because a lot of the operations (e.g. mkdir) are restartable if we
     haven't yet started sending the op to the server.

Fixes: e49c7b2f6d ("afs: Build an abstraction around an "operation" concept")
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
David Howells 2020-07-08 09:27:07 +01:00 committed by Linus Torvalds
parent e9919e11e2
commit 811f04bac1
2 changed files with 3 additions and 2 deletions
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4
fs/afs/fs_operation.c
View File

@ -71,7 +71,7 @@ static bool afs_get_io_locks(struct afs_operation *op)
swap(vnode, vnode2);
if (mutex_lock_interruptible(&vnode->io_lock) < 0) {
op->error = -EINTR;
op->error = -ERESTARTSYS;
op->flags |= AFS_OPERATION_STOP;
_leave(" = f [I 0]");
return false;
@ -80,7 +80,7 @@ static bool afs_get_io_locks(struct afs_operation *op)
if (vnode2) {
if (mutex_lock_interruptible_nested(&vnode2->io_lock, 1) < 0) {
op->error = -EINTR;
op->error = -ERESTARTSYS;
op->flags |= AFS_OPERATION_STOP;
mutex_unlock(&vnode->io_lock);
op->flags &= ~AFS_OPERATION_LOCK_0;

1
fs/afs/write.c
View File

@ -449,6 +449,7 @@ static int afs_store_data(struct address_space *mapping,
op->store.first_offset = offset;
op->store.last_to = to;
op->mtime = vnode->vfs_inode.i_mtime;
op->flags |= AFS_OPERATION_UNINTR;
op->ops = &afs_store_data_operation;
try_next_key: