On Mon, Nov 14, 2011 at 07:10:28PM +0800, Jan Kara wrote:
>
> Hello,
>
> these two patches aim at making task waiting in balance_dirty_pages()
> killable. This is desirable because otherwise if filesystem stops accepting
> writes (e.g. if device has been removed or other serious error condidion) we
> have a task stuck in D state forever.
Agreed totally. I myself has run into such conditions and get very
annoyed not being able to kill the hard throttled tasks -- they just
stuck there for ever if the error condition does not change.
> I'm not sure who should merge these two patches... Al, Fengguang?
I'd like to do it -- otherwise there will obviously be merge conflicts.
Actually I also queued a patch to do this (attached). Your patches do
better on TASK_KILLABLE and the use of signal_pending() in write
routines, while mine goes further to add the break to various
filesystems. How about combining them together?
Thanks,
Fengguang
Subject: writeback: quit throttling when fatal signal pending
Date: Wed Sep 08 17:40:22 CST 2010
This allows quick response to Ctrl-C etc. for impatient users.
It's necessary to abort the generic_perform_write() and other filesystem
write loops too, to avoid large write + SIGKILL combination exceeding
the dirty limit and possibly strange OOM.
It mainly helps the rare bdi/global dirty exceeded cases.
In the normal case of not exceeded, it will quit the loop anyway.
if (fatal_signal_pending(current) &&
nr_reclaimable + nr_writeback <= dirty_thresh)
break;
Reviewed-by: Neil Brown <neilb@xxxxxxx>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
cc: Chris Mason <chris.mason@xxxxxxxxxx>
cc: Anton Altaparmakov <aia21@xxxxxxxxxx>
Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx>
---
fs/btrfs/file.c | 4 ++++
fs/btrfs/ioctl.c | 4 ++++
fs/btrfs/relocation.c | 4 ++++
fs/buffer.c | 4 ++++
fs/ntfs/attrib.c | 2 ++
fs/ntfs/file.c | 6 ++++++
mm/filemap.c | 3 ++-
mm/page-writeback.c | 2 ++
8 files changed, 28 insertions(+), 1 deletion(-)
--- linux-next.orig/mm/page-writeback.c 2011-11-13 20:37:11.000000000 +0800
+++ linux-next/mm/page-writeback.c 2011-11-13 20:37:57.000000000 +0800
@@ -1185,6 +1185,8 @@ pause:
*/
if (task_ratelimit)
break;
+ if (fatal_signal_pending(current))
+ break;
}
if (!dirty_exceeded && bdi->dirty_exceeded)
--- linux-next.orig/mm/filemap.c 2011-11-13 20:03:23.000000000 +0800
+++ linux-next/mm/filemap.c 2011-11-13 20:37:17.000000000 +0800
@@ -2463,7 +2463,8 @@ again:
written += copied;
balance_dirty_pages_ratelimited(mapping);
-
+ if (fatal_signal_pending(current))
+ break;
} while (iov_iter_count(i));
return written ? written : status;
--- linux-next.orig/fs/btrfs/file.c 2011-11-13 20:37:11.000000000 +0800
+++ linux-next/fs/btrfs/file.c 2011-11-13 20:37:17.000000000 +0800
@@ -1274,6 +1274,10 @@ static noinline ssize_t __btrfs_buffered
dirty_pages);
if (dirty_pages < (root->leafsize >> PAGE_CACHE_SHIFT) + 1)
btrfs_btree_balance_dirty(root, 1);
+ if (fatal_signal_pending(current)) {
+ ret = -EINTR;
+ break;
+ }
btrfs_throttle(root);
pos += copied;
--- linux-next.orig/fs/btrfs/ioctl.c 2011-11-13 20:03:23.000000000 +0800
+++ linux-next/fs/btrfs/ioctl.c 2011-11-13 20:37:17.000000000 +0800
@@ -1115,6 +1115,10 @@ int btrfs_defrag_file(struct inode *inod
defrag_count += ret;
balance_dirty_pages_ratelimited_nr(inode->i_mapping, ret);
+ if (fatal_signal_pending(current)) {
+ ret = -EINTR;
+ goto out_ra;
+ }
if (newer_than) {
if (newer_off == (u64)-1)
--- linux-next.orig/fs/btrfs/relocation.c 2011-11-13 20:03:23.000000000 +0800
+++ linux-next/fs/btrfs/relocation.c 2011-11-13 20:37:17.000000000 +0800
@@ -3009,6 +3009,10 @@ static int relocate_file_extent_cluster(
index++;
balance_dirty_pages_ratelimited(inode->i_mapping);
+ if (fatal_signal_pending(current)) {
+ ret = -EINTR;
+ break;
+ }
btrfs_throttle(BTRFS_I(inode)->root);
}
WARN_ON(nr != cluster->nr);
--- linux-next.orig/fs/buffer.c 2011-11-13 20:03:23.000000000 +0800
+++ linux-next/fs/buffer.c 2011-11-13 20:37:17.000000000 +0800
@@ -2255,6 +2255,10 @@ static int cont_expand_zero(struct file
err = 0;
balance_dirty_pages_ratelimited(mapping);
+ if (fatal_signal_pending(current)) {
+ err = -EINTR;
+ goto out;
+ }
}
/* page covers the boundary, find the boundary offset */
--- linux-next.orig/fs/ntfs/attrib.c 2011-11-13 20:03:23.000000000 +0800
+++ linux-next/fs/ntfs/attrib.c 2011-11-13 20:37:17.000000000 +0800
@@ -2588,6 +2588,8 @@ int ntfs_attr_set(ntfs_inode *ni, const
unlock_page(page);
page_cache_release(page);
balance_dirty_pages_ratelimited(mapping);
+ if (fatal_signal_pending(current))
+ return -EINTR;
cond_resched();
}
/* If there is a last partial page, need to do it the slow way. */
--- linux-next.orig/fs/ntfs/file.c 2011-11-13 20:03:23.000000000 +0800
+++ linux-next/fs/ntfs/file.c 2011-11-13 20:37:17.000000000 +0800
@@ -278,6 +278,10 @@ do_non_resident_extend:
* files.
*/
balance_dirty_pages_ratelimited(mapping);
+ if (fatal_signal_pending(current)) {
+ err = -EINTR;
+ goto init_err_out;
+ }
cond_resched();
} while (++index < end_index);
read_lock_irqsave(&ni->size_lock, flags);
@@ -2054,6 +2058,8 @@ static ssize_t ntfs_file_buffered_write(
if (unlikely(status))
break;
balance_dirty_pages_ratelimited(mapping);
+ if (fatal_signal_pending(current))
+ break;
cond_resched();
} while (count);
err_out:
