afs: Make some RPC operations non-interruptible

Make certain RPC operations non-interruptible, including:

 (*) Set attributes
 (*) Store data

     We don't want to get interrupted during a flush on close, flush on
     unlock, writeback or an inode update, leaving us in a state where we
     still need to do the writeback or update.

 (*) Extend lock
 (*) Release lock

     We don't want to get lock extension interrupted as the file locks on
     the server are time-limited.  Interruption during lock release is less
     of an issue since the lock is time-limited, but it's better to
     complete the release to avoid a several-minute wait to recover it.

     *Setting* the lock isn't a problem if it's interrupted since we can
      just return to the user and tell them they were interrupted - at
      which point they can elect to retry.

 (*) Silly unlink

     We want to remove silly unlink files if we can, rather than leaving
     them for the salvager to clear up.

Note that whilst these calls are no longer interruptible, they do have
timeouts on them, so if the server stops responding the call will fail with
something like ETIME or ECONNRESET.

Without this, the following:

	kAFS: Unexpected error from FS.StoreData -512

appears in dmesg when a pending store data gets interrupted and some
processes may just hang.

Additionally, make the code that checks/updates the server record ignore
failure due to interruption if the main call is uninterruptible and if the
server has an address list.  The next op will check it again since the
expiration time on the old list has past.

Fixes: d2ddc776a458 ("afs: Overhaul volume and server record caching and fileserver rotation")
Reported-by: Jonathan Billings <jsbillings@jsbillings.org>
Reported-by: Marc Dionne <marc.dionne@auristor.com>
Signed-off-by: David Howells <dhowells@redhat.com>

1 files changed, 8 insertions, 1 deletions

diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index 4765c6716242..833fa39ee337 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -149,6 +149,7 @@ struct afs_call {
 	bool			ret_reply0;	/* T if should return reply[0] on success */
 	bool			upgrade;	/* T to request service upgrade */
 	bool			want_reply_time; /* T if want reply_time */
+	bool			intr;		/* T if interruptible */
 	u16			service_id;	/* Actual service ID (after upgrade) */
 	unsigned int		debug_id;	/* Trace ID */
 	u32			operation_ID;	/* operation ID for an incoming call */
@@ -773,6 +774,7 @@ struct afs_fs_cursor {
 #define AFS_FS_CURSOR_VNOVOL	0x0008		/* Set if seen VNOVOL */
 #define AFS_FS_CURSOR_CUR_ONLY	0x0010		/* Set if current server only (file lock held) */
 #define AFS_FS_CURSOR_NO_VSLEEP	0x0020		/* Set to prevent sleep on VBUSY, VOFFLINE, ... */
+#define AFS_FS_CURSOR_INTR	0x0040		/* Set if op is interruptible */
 	unsigned short		nr_iterations;	/* Number of server iterations */
 };
 
@@ -1097,7 +1099,7 @@ static inline void afs_put_sysnames(struct afs_sysnames *sysnames) {}
  * rotate.c
  */
 extern bool afs_begin_vnode_operation(struct afs_fs_cursor *, struct afs_vnode *,
-				      struct key *);
+				      struct key *, bool);
 extern bool afs_select_fileserver(struct afs_fs_cursor *);
 extern bool afs_select_current_fileserver(struct afs_fs_cursor *);
 extern int afs_end_vnode_operation(struct afs_fs_cursor *);
@@ -1122,6 +1124,11 @@ extern void afs_send_simple_reply(struct afs_call *, const void *, size_t);
 extern int afs_extract_data(struct afs_call *, bool);
 extern int afs_protocol_error(struct afs_call *, int, enum afs_eproto_cause);
 
+static inline void afs_set_fc_call(struct afs_call *call, struct afs_fs_cursor *fc)
+{
+	call->intr = fc->flags & AFS_FS_CURSOR_INTR;
+}
+
 static inline void afs_extract_begin(struct afs_call *call, void *buf, size_t size)
 {
 	call->kvec[0].iov_base = buf;