Just only typos
On the 18.10.2010 08:20, Dave Chinner wrote:
From: Dave Chinner<dchinner@xxxxxxxxxx>
Given that the inode LRU and IO lists are split apart, they do not
need to be protected by the same lock. So in preparation for removal
of the inode_lock, add new locks for them. The writeback lists are
only ever accessed in the context of a bdi, so add a per-BDI lock to
protect manipulations of these lists.
For the inode LRU, introduce a simple global lock to protect it.
While this could be made per-sb, it is unclear yet as to what is the
next step for optimising/parallelising reclaim of inodes. Rather
than optimise now, leave it as a global list and lock until further
analysis can be done.
Because there will now be a situation where the inode is on
different lists protected by different locks during the freeing of
the inode (i.e. not an atomic state transition), we need to ensure
that we set the I_FREEING state flag before we start removing inodes
from the IO and LRU lists. This ensures that if we race with other
threads during freeing, they will notice the I_FREEING flag is set
and be able to take appropriate action to avoid problems.
Based on a patch originally from Nick Piggin.
Signed-off-by: Dave Chinner<dchinner@xxxxxxxxxx>
Reviewed-by: Christoph Hellwig<hch@xxxxxx>
---
fs/block_dev.c | 5 +++
fs/fs-writeback.c | 51 +++++++++++++++++++++++++++++++++---
fs/inode.c | 61 ++++++++++++++++++++++++++++++++++++++-----
fs/internal.h | 5 +++
include/linux/backing-dev.h | 3 ++
mm/backing-dev.c | 19 +++++++++++++
6 files changed, 133 insertions(+), 11 deletions(-)
diff --git a/fs/block_dev.c b/fs/block_dev.c
index 11ad53d..7909775 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -56,10 +56,15 @@ EXPORT_SYMBOL(I_BDEV);
static void bdev_inode_switch_bdi(struct inode *inode,
struct backing_dev_info *dst)
{
+ struct backing_dev_info *old = inode->i_data.backing_dev_info;
+
spin_lock(&inode_lock);
+ bdi_lock_two(old, dst);
inode->i_data.backing_dev_info = dst;
if (!list_empty(&inode->i_wb_list))
list_move(&inode->i_wb_list,&dst->wb.b_dirty);
+ spin_unlock(&old->wb.b_lock);
+ spin_unlock(&dst->wb.b_lock);
spin_unlock(&inode_lock);
}
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 676e048..f159141 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -157,6 +157,18 @@ void bdi_start_background_writeback(struct backing_dev_info *bdi)
}
/*
+ * Remove the inode from the writeback list it is on.
+ */
+void inode_wb_list_del(struct inode *inode)
+{
+ struct backing_dev_info *bdi = inode_to_bdi(inode);
+
+ spin_lock(&bdi->wb.b_lock);
+ list_del_init(&inode->i_wb_list);
+ spin_unlock(&bdi->wb.b_lock);
+}
+
+/*
* Redirty an inode: set its when-it-was dirtied timestamp and move it to the
* furthest end of its superblock's dirty-inode list.
*
@@ -169,6 +181,7 @@ static void redirty_tail(struct inode *inode)
{
struct bdi_writeback *wb =&inode_to_bdi(inode)->wb;
+ assert_spin_locked(&wb->b_lock);
if (!list_empty(&wb->b_dirty)) {
struct inode *tail;
@@ -186,6 +199,7 @@ static void requeue_io(struct inode *inode)
{
struct bdi_writeback *wb =&inode_to_bdi(inode)->wb;
+ assert_spin_locked(&wb->b_lock);
list_move(&inode->i_wb_list,&wb->b_more_io);
}
@@ -269,6 +283,7 @@ static void move_expired_inodes(struct list_head *delaying_queue,
*/
static void queue_io(struct bdi_writeback *wb, unsigned long *older_than_this)
{
+ assert_spin_locked(&wb->b_lock);
list_splice_init(&wb->b_more_io,&wb->b_io);
move_expired_inodes(&wb->b_dirty,&wb->b_io, older_than_this);
}
@@ -311,6 +326,7 @@ static void inode_wait_for_writeback(struct inode *inode)
static int
writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
{
+ struct backing_dev_info *bdi = inode_to_bdi(inode);
struct address_space *mapping = inode->i_mapping;
unsigned dirty;
int ret;
@@ -330,7 +346,9 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
* completed a full scan of b_io.
*/
if (wbc->sync_mode != WB_SYNC_ALL) {
+ spin_lock(&bdi->wb.b_lock);
requeue_io(inode);
+ spin_unlock(&bdi->wb.b_lock);
return 0;
}
@@ -385,6 +403,7 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
* sometimes bales out without doing anything.
*/
inode->i_state |= I_DIRTY_PAGES;
+ spin_lock(&bdi->wb.b_lock);
if (wbc->nr_to_write<= 0) {
/*
* slice used up: queue for next turn
@@ -400,6 +419,7 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
*/
redirty_tail(inode);
}
+ spin_unlock(&bdi->wb.b_lock);
} else if (inode->i_state& I_DIRTY) {
/*
* Filesystems can dirty the inode during writeback
@@ -407,7 +427,9 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
* submission or metadata updates after data IO
* completion.
*/
+ spin_lock(&bdi->wb.b_lock);
redirty_tail(inode);
+ spin_unlock(&bdi->wb.b_lock);
} else {
/*
* The inode is clean. If it is unused, then make sure
@@ -415,7 +437,7 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
* does not move dirty inodes to the LRU and dirty
* inodes are removed from the LRU during scanning.
*/
- list_del_init(&inode->i_wb_list);
+ inode_wb_list_del(inode);
if (!inode->i_ref)
inode_lru_list_add(inode);
}
@@ -463,6 +485,7 @@ static bool pin_sb_for_writeback(struct super_block *sb)
static int writeback_sb_inodes(struct super_block *sb, struct bdi_writeback *wb,
struct writeback_control *wbc, bool only_this_sb)
{
+ assert_spin_locked(&wb->b_lock);
while (!list_empty(&wb->b_io)) {
long pages_skipped;
struct inode *inode = list_entry(wb->b_io.prev,
@@ -478,7 +501,6 @@ static int writeback_sb_inodes(struct super_block *sb, struct bdi_writeback *wb,
redirty_tail(inode);
continue;
}
-
/*
* The inode belongs to a different superblock.
* Bounce back to the caller to unpin this and
@@ -487,7 +509,15 @@ static int writeback_sb_inodes(struct super_block *sb, struct bdi_writeback *wb,
return 0;
}
- if (inode->i_state& (I_NEW | I_WILL_FREE)) {
+ /*
+ * We can see I_FREEING here when the inod isin the process of
is in
+ * being reclaimed. In that case the freer is waiting on the
+ * wb->b_lock that we currently hold to remove the inode from
+ * the writeback list. So we don't spin on it here, requeue it
+ * and move on to the next inode, which will allow the other
+ * thread to free the inode when we drop the lock.
+ */
[...]
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