linux-toradex.git/include/linux/writeback.h, branch v2.6.36-rc7

writeback: avoid unnecessary calculation of bdi dirty thresholds

2010-08-12T15:43:29+00:00

Split get_dirty_limits() into global_dirty_limits()+bdi_dirty_limit(), so
that the latter can be avoided when under global dirty background
threshold (which is the normal state for most systems).

Signed-off-by: Wu Fengguang 
Cc: Peter Zijlstra 
Cc: Christoph Hellwig 
Cc: Dave Chinner 
Cc: Jens Axboe 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

writeback: split writeback_inodes_wb

2010-07-06T06:54:08+00:00

The case where we have a superblock doesn't require a loop here as we scan
over all inodes in writeback_sb_inodes. Split it out into a separate helper
to make the code simpler.  This also allows to get rid of the sb member in
struct writeback_control, which was rather out of place there.

Also update the comments in writeback_sb_inodes that explain the handling
of inodes from wrong superblocks.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Jens Axboe

writeback: remove writeback_inodes_wbc

2010-07-06T06:54:03+00:00

This was just an odd wrapper around writeback_inodes_wb.  Removing this
also allows to get rid of the bdi member of struct writeback_control
which was rather out of place there.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Jens Axboe

writeback: pay attention to wbc->nr_to_write in write_cache_pages

2010-06-09T01:12:44+00:00

If a filesystem writes more than one page in ->writepage, write_cache_pages
fails to notice this and continues to attempt writeback when wbc->nr_to_write
has gone negative - this trace was captured from XFS:

    wbc_writeback_start: towrt=1024
    wbc_writepage: towrt=1024
    wbc_writepage: towrt=0
    wbc_writepage: towrt=-1
    wbc_writepage: towrt=-5
    wbc_writepage: towrt=-21
    wbc_writepage: towrt=-85

This has adverse effects on filesystem writeback behaviour. write_cache_pages()
needs to terminate after a certain number of pages are written, not after a
certain number of calls to ->writepage are made.  This is a regression
introduced by 17bc6c30cf6bfffd816bdc53682dd46fc34a2cf4 ("vfs: Add
no_nrwrite_index_update writeback control flag"), but cannot be reverted
directly due to subsequent bug fixes that have gone in on top of it.

Signed-off-by: Dave Chinner 
Reviewed-by: Christoph Hellwig 
Signed-off-by: Linus Torvalds

Revert "writeback: fix WB_SYNC_NONE writeback from umount"

2010-06-01T09:08:43+00:00

This reverts commit e913fc825dc685a444cb4c1d0f9d32f372f59861.

We are investigating a hang associated with the WB_SYNC_NONE changes,
so revert them for now.

Conflicts:

	fs/fs-writeback.c
	mm/page-writeback.c

Signed-off-by: Jens Axboe

writeback: fix problem with !CONFIG_BLOCK compilation

2010-05-21T18:01:03+00:00

When CONFIG_BLOCK isn't enabled:

mm/page-writeback.c: In function 'laptop_mode_timer_fn':
mm/page-writeback.c:708: error: dereferencing pointer to incomplete type
mm/page-writeback.c:709: error: dereferencing pointer to incomplete type

Fix this by essentially eliminating the laptop sync handlers when
CONFIG_BLOCK isn't set, as most are only used from the block layer code.
The exception is laptop_sync_completion() which is used from sys_sync(),
make that an empty declaration in that case.

Reported-by: Randy Dunlap 
Signed-off-by: Jens Axboe

writeback: fix WB_SYNC_NONE writeback from umount

2010-05-17T10:55:07+00:00

When umount calls sync_filesystem(), we first do a WB_SYNC_NONE
writeback to kick off writeback of pending dirty inodes, then follow
that up with a WB_SYNC_ALL to wait for it. Since umount already holds
the sb s_umount mutex, WB_SYNC_NONE ends up doing nothing and all
writeback happens as WB_SYNC_ALL. This can greatly slow down umount,
since WB_SYNC_ALL writeback is a data integrity operation and thus
a bigger hammer than simple WB_SYNC_NONE. For barrier aware file systems
it's a lot slower.

Signed-off-by: Jens Axboe

laptop-mode: Make flushes per-device

2010-04-06T12:25:14+00:00

One of the features of laptop-mode is that it forces a writeout of dirty
pages if something else triggers a physical read or write from a device.
The current implementation flushes pages on all devices, rather than only
the one that triggered the flush. This patch alters the behaviour so that
only the recently accessed block device is flushed, preventing other
disks being spun up for no terribly good reason.

Signed-off-by: Matthew Garrett 
Signed-off-by: Jens Axboe

vfs: improve writeback_inodes_wb()

2010-03-12T09:03:42+00:00

Do not pin/unpin superblock for every inode in writeback_inodes_wb(), pin
it for the whole group of inodes which belong to the same superblock and
call writeback_sb_inodes() handler for them.

Signed-off-by: Edward Shishkin 
Cc: Jens Axboe 
Cc: Wu Fengguang 
Signed-off-by: Andrew Morton 
Signed-off-by: Jens Axboe

fs-writeback: Add helper function to start writeback if idle

2009-12-23T12:57:07+00:00

ext4, at least, would like to start pushing on writeback if it starts
to get close to ENOSPC when reserving worst-case blocks for delalloc
writes.  Writing out delalloc data will convert those worst-case
predictions into usually smaller actual usage, freeing up space
before we hit ENOSPC based on this speculation.

Thanks to Jens for the suggestion for the helper function,
& the naming help.

I've made the helper return status on whether writeback was
started even though I don't plan to use it in the ext4 patch;
it seems like it would be potentially useful to test this
in some cases.

Signed-off-by: Eric Sandeen 
Acked-by: Jan Kara