[PATCH 24/27] afs: afs_fsync() does two flushes, one of which is redundant
From: David Howells
Date: Thu Mar 09 2017 - 13:58:46 EST
afs_fsync() calls filemap_write_and_wait_range() and then does a walk
through the writeback records and flushes those - which should achieve
exactly the same thing.
Get rid of the filemap_write_and_wait_range() since that's uninterruptible,
whereas the wait for the writeback records is interruptible.
Further, we can at least contract the inode-locked region to just the
afs_writeback_call().
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
---
fs/afs/write.c | 61 ++++++++++++++++++++++++++++++++++++--------------------
1 file changed, 39 insertions(+), 22 deletions(-)
diff --git a/fs/afs/write.c b/fs/afs/write.c
index 6e13e96c3db0..ab89551ab356 100644
--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -700,21 +700,17 @@ int afs_writeback_all(struct afs_vnode *vnode)
* - the return status from this call provides a reliable indication of
* whether any write errors occurred for this process.
*/
-int afs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
+static int afs_sync_file(struct file *file, loff_t start, loff_t end, bool sync)
{
struct inode *inode = file_inode(file);
struct afs_writeback *wb, *xwb;
struct afs_vnode *vnode = AFS_FS_I(inode);
+ bool do_sync = false;
int ret;
_enter("{%x:%u},{n=%pD},%d",
vnode->fid.vid, vnode->fid.vnode, file,
- datasync);
-
- ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
- if (ret)
- return ret;
- inode_lock(inode);
+ sync);
/* use a writeback record as a marker in the queue - when this reaches
* the front of the queue, all the outstanding writes are either
@@ -732,34 +728,55 @@ int afs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
wb->usage = 1;
wb->state = AFS_WBACK_SYNCING;
init_waitqueue_head(&wb->waitq);
+ INIT_LIST_HEAD(&wb->link);
spin_lock(&vnode->writeback_lock);
list_for_each_entry(xwb, &vnode->writebacks, link) {
- if (xwb->state == AFS_WBACK_PENDING)
+ switch (xwb->state) {
+ case AFS_WBACK_PENDING:
xwb->state = AFS_WBACK_CONFLICTING;
+ do_sync = true;
+ break;
+ default:
+ do_sync |= sync;
+ break;
+ case AFS_WBACK_SYNCING:
+ break;
+ case AFS_WBACK_COMPLETE:
+ kdebug("Shouldn't see completed records");
+ break;
+ }
}
- list_add_tail(&wb->link, &vnode->writebacks);
+ if (do_sync)
+ list_add_tail(&wb->link, &vnode->writebacks);
spin_unlock(&vnode->writeback_lock);
- /* push all the outstanding writebacks to the server */
- ret = afs_writeback_all(vnode);
- if (ret < 0) {
- afs_put_writeback(wb);
- _leave(" = %d [wb]", ret);
- goto out;
+ ret = 0;
+ if (do_sync) {
+ /* push all the outstanding writebacks to the server */
+ inode_lock(inode);
+ ret = afs_writeback_all(vnode);
+ inode_unlock(inode);
+ if (ret < 0)
+ goto out;
+
+ /* wait for the preceding writes to actually complete */
+ ret = wait_event_interruptible(wb->waitq,
+ wb->state == AFS_WBACK_COMPLETE ||
+ vnode->writebacks.next == &wb->link);
}
- /* wait for the preceding writes to actually complete */
- ret = wait_event_interruptible(wb->waitq,
- wb->state == AFS_WBACK_COMPLETE ||
- vnode->writebacks.next == &wb->link);
+out:
afs_put_writeback(wb);
_leave(" = %d", ret);
-out:
- inode_unlock(inode);
return ret;
}
+int afs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
+{
+ return afs_sync_file(file, start, end, true);
+}
+
/*
* Flush out all outstanding writes on a file opened for writing when it is
* closed.
@@ -771,7 +788,7 @@ int afs_flush(struct file *file, fl_owner_t id)
if ((file->f_mode & FMODE_WRITE) == 0)
return 0;
- return vfs_fsync(file, 0);
+ return afs_sync_file(file, 0, LLONG_MAX, false);
}
/*