From 743162013d40ca612b4cb53d3a200dff2d9ab26e Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Mon, 7 Jul 2014 15:16:04 +1000 Subject: sched: Remove proliferation of wait_on_bit() action functions The current "wait_on_bit" interface requires an 'action' function to be provided which does the actual waiting. There are over 20 such functions, many of them identical. Most cases can be satisfied by one of just two functions, one which uses io_schedule() and one which just uses schedule(). So: Rename wait_on_bit and wait_on_bit_lock to wait_on_bit_action and wait_on_bit_lock_action to make it explicit that they need an action function. Introduce new wait_on_bit{,_lock} and wait_on_bit{,_lock}_io which are *not* given an action function but implicitly use a standard one. The decision to error-out if a signal is pending is now made based on the 'mode' argument rather than being encoded in the action function. All instances of the old wait_on_bit and wait_on_bit_lock which can use the new version have been changed accordingly and their action functions have been discarded. wait_on_bit{_lock} does not return any specific error code in the event of a signal so the caller must check for non-zero and interpolate their own error code as appropriate. The wait_on_bit() call in __fscache_wait_on_invalidate() was ambiguous as it specified TASK_UNINTERRUPTIBLE but used fscache_wait_bit_interruptible as an action function. David Howells confirms this should be uniformly "uninterruptible" The main remaining user of wait_on_bit{,_lock}_action is NFS which needs to use a freezer-aware schedule() call. A comment in fs/gfs2/glock.c notes that having multiple 'action' functions is useful as they display differently in the 'wchan' field of 'ps'. (and /proc/$PID/wchan). As the new bit_wait{,_io} functions are tagged "__sched", they will not show up at all, but something higher in the stack. So the distinction will still be visible, only with different function names (gds2_glock_wait versus gfs2_glock_dq_wait in the gfs2/glock.c case). Since first version of this patch (against 3.15) two new action functions appeared, on in NFS and one in CIFS. CIFS also now uses an action function that makes the same freezer aware schedule call as NFS. Signed-off-by: NeilBrown Acked-by: David Howells (fscache, keys) Acked-by: Steven Whitehouse (gfs2) Acked-by: Peter Zijlstra Cc: Oleg Nesterov Cc: Steve French Cc: Linus Torvalds Link: http://lkml.kernel.org/r/20140707051603.28027.72349.stgit@notabene.brown Signed-off-by: Ingo Molnar --- fs/cifs/connect.c | 10 +--------- fs/cifs/file.c | 9 +-------- fs/cifs/inode.c | 4 ++-- fs/cifs/misc.c | 2 +- 4 files changed, 5 insertions(+), 20 deletions(-) (limited to 'fs/cifs') diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c index 20d75b8ddb26..b98366f21f9e 100644 --- a/fs/cifs/connect.c +++ b/fs/cifs/connect.c @@ -3934,13 +3934,6 @@ cifs_sb_master_tcon(struct cifs_sb_info *cifs_sb) return tlink_tcon(cifs_sb_master_tlink(cifs_sb)); } -static int -cifs_sb_tcon_pending_wait(void *unused) -{ - schedule(); - return signal_pending(current) ? -ERESTARTSYS : 0; -} - /* find and return a tlink with given uid */ static struct tcon_link * tlink_rb_search(struct rb_root *root, kuid_t uid) @@ -4039,11 +4032,10 @@ cifs_sb_tlink(struct cifs_sb_info *cifs_sb) } else { wait_for_construction: ret = wait_on_bit(&tlink->tl_flags, TCON_LINK_PENDING, - cifs_sb_tcon_pending_wait, TASK_INTERRUPTIBLE); if (ret) { cifs_put_tlink(tlink); - return ERR_PTR(ret); + return ERR_PTR(-ERESTARTSYS); } /* if it's good, return it */ diff --git a/fs/cifs/file.c b/fs/cifs/file.c index e90a1e9aa627..b88b1ade4d3d 100644 --- a/fs/cifs/file.c +++ b/fs/cifs/file.c @@ -3618,13 +3618,6 @@ static int cifs_launder_page(struct page *page) return rc; } -static int -cifs_pending_writers_wait(void *unused) -{ - schedule(); - return 0; -} - void cifs_oplock_break(struct work_struct *work) { struct cifsFileInfo *cfile = container_of(work, struct cifsFileInfo, @@ -3636,7 +3629,7 @@ void cifs_oplock_break(struct work_struct *work) int rc = 0; wait_on_bit(&cinode->flags, CIFS_INODE_PENDING_WRITERS, - cifs_pending_writers_wait, TASK_UNINTERRUPTIBLE); + TASK_UNINTERRUPTIBLE); server->ops->downgrade_oplock(server, cinode, test_bit(CIFS_INODE_DOWNGRADE_OPLOCK_TO_L2, &cinode->flags)); diff --git a/fs/cifs/inode.c b/fs/cifs/inode.c index a174605f6afa..213c4580b4e3 100644 --- a/fs/cifs/inode.c +++ b/fs/cifs/inode.c @@ -1794,8 +1794,8 @@ cifs_revalidate_mapping(struct inode *inode) int rc; unsigned long *flags = &CIFS_I(inode)->flags; - rc = wait_on_bit_lock(flags, CIFS_INO_LOCK, cifs_wait_bit_killable, - TASK_KILLABLE); + rc = wait_on_bit_lock_action(flags, CIFS_INO_LOCK, cifs_wait_bit_killable, + TASK_KILLABLE); if (rc) return rc; diff --git a/fs/cifs/misc.c b/fs/cifs/misc.c index 3b0c62e622da..6bf55d0ed494 100644 --- a/fs/cifs/misc.c +++ b/fs/cifs/misc.c @@ -582,7 +582,7 @@ int cifs_get_writer(struct cifsInodeInfo *cinode) start: rc = wait_on_bit(&cinode->flags, CIFS_INODE_PENDING_OPLOCK_BREAK, - cifs_oplock_break_wait, TASK_KILLABLE); + TASK_KILLABLE); if (rc) return rc; -- cgit v1.2.3