GFS2: Make writeback more responsive to system conditions
This patch adds writeback_control to writing back the AIL
list. This means that we can then take advantage of the
information we get in ->write_inode() in order to set off
some pre-emptive writeback.
In addition, the AIL code is cleaned up a bit to make it
a bit simpler to understand.
There is still more which can usefully be done in this area,
but this is a good start at least.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
diff --git a/fs/gfs2/log.c b/fs/gfs2/log.c
index 3ebafa1..03e0041 100644
--- a/fs/gfs2/log.c
+++ b/fs/gfs2/log.c
@@ -18,6 +18,7 @@
#include <linux/kthread.h>
#include <linux/freezer.h>
#include <linux/bio.h>
+#include <linux/writeback.h>
#include "gfs2.h"
#include "incore.h"
@@ -83,50 +84,90 @@
/**
* gfs2_ail1_start_one - Start I/O on a part of the AIL
* @sdp: the filesystem
- * @tr: the part of the AIL
+ * @wbc: The writeback control structure
+ * @ai: The ail structure
*
*/
-static void gfs2_ail1_start_one(struct gfs2_sbd *sdp, struct gfs2_ail *ai)
+static void gfs2_ail1_start_one(struct gfs2_sbd *sdp,
+ struct writeback_control *wbc,
+ struct gfs2_ail *ai)
__releases(&sdp->sd_ail_lock)
__acquires(&sdp->sd_ail_lock)
{
struct gfs2_glock *gl = NULL;
+ struct address_space *mapping;
struct gfs2_bufdata *bd, *s;
struct buffer_head *bh;
- int retry;
- do {
- retry = 0;
+restart:
+ list_for_each_entry_safe_reverse(bd, s, &ai->ai_ail1_list, bd_ail_st_list) {
+ bh = bd->bd_bh;
- list_for_each_entry_safe_reverse(bd, s, &ai->ai_ail1_list,
- bd_ail_st_list) {
- bh = bd->bd_bh;
+ gfs2_assert(sdp, bd->bd_ail == ai);
- gfs2_assert(sdp, bd->bd_ail == ai);
-
- if (!buffer_busy(bh)) {
- if (!buffer_uptodate(bh))
- gfs2_io_error_bh(sdp, bh);
- list_move(&bd->bd_ail_st_list, &ai->ai_ail2_list);
- continue;
- }
-
- if (!buffer_dirty(bh))
- continue;
- if (gl == bd->bd_gl)
- continue;
- gl = bd->bd_gl;
- list_move(&bd->bd_ail_st_list, &ai->ai_ail1_list);
-
- spin_unlock(&sdp->sd_ail_lock);
- filemap_fdatawrite(gfs2_glock2aspace(gl));
- spin_lock(&sdp->sd_ail_lock);
-
- retry = 1;
- break;
+ if (!buffer_busy(bh)) {
+ if (!buffer_uptodate(bh))
+ gfs2_io_error_bh(sdp, bh);
+ list_move(&bd->bd_ail_st_list, &ai->ai_ail2_list);
+ continue;
}
- } while (retry);
+
+ if (!buffer_dirty(bh))
+ continue;
+ if (gl == bd->bd_gl)
+ continue;
+ gl = bd->bd_gl;
+ list_move(&bd->bd_ail_st_list, &ai->ai_ail1_list);
+ mapping = bh->b_page->mapping;
+ spin_unlock(&sdp->sd_ail_lock);
+ generic_writepages(mapping, wbc);
+ spin_lock(&sdp->sd_ail_lock);
+ if (wbc->nr_to_write <= 0)
+ break;
+ goto restart;
+ }
+}
+
+
+/**
+ * gfs2_ail1_flush - start writeback of some ail1 entries
+ * @sdp: The super block
+ * @wbc: The writeback control structure
+ *
+ * Writes back some ail1 entries, according to the limits in the
+ * writeback control structure
+ */
+
+void gfs2_ail1_flush(struct gfs2_sbd *sdp, struct writeback_control *wbc)
+{
+ struct list_head *head = &sdp->sd_ail1_list;
+ struct gfs2_ail *ai;
+
+ spin_lock(&sdp->sd_ail_lock);
+ list_for_each_entry_reverse(ai, head, ai_list) {
+ if (wbc->nr_to_write <= 0)
+ break;
+ gfs2_ail1_start_one(sdp, wbc, ai); /* This may drop ail lock */
+ }
+ spin_unlock(&sdp->sd_ail_lock);
+}
+
+/**
+ * gfs2_ail1_start - start writeback of all ail1 entries
+ * @sdp: The superblock
+ */
+
+static void gfs2_ail1_start(struct gfs2_sbd *sdp)
+{
+ struct writeback_control wbc = {
+ .sync_mode = WB_SYNC_NONE,
+ .nr_to_write = LONG_MAX,
+ .range_start = 0,
+ .range_end = LLONG_MAX,
+ };
+
+ return gfs2_ail1_flush(sdp, &wbc);
}
/**
@@ -136,7 +177,7 @@
*
*/
-static int gfs2_ail1_empty_one(struct gfs2_sbd *sdp, struct gfs2_ail *ai, int flags)
+static void gfs2_ail1_empty_one(struct gfs2_sbd *sdp, struct gfs2_ail *ai)
{
struct gfs2_bufdata *bd, *s;
struct buffer_head *bh;
@@ -144,71 +185,37 @@
list_for_each_entry_safe_reverse(bd, s, &ai->ai_ail1_list,
bd_ail_st_list) {
bh = bd->bd_bh;
-
gfs2_assert(sdp, bd->bd_ail == ai);
-
- if (buffer_busy(bh)) {
- if (flags & DIO_ALL)
- continue;
- else
- break;
- }
-
+ if (buffer_busy(bh))
+ continue;
if (!buffer_uptodate(bh))
gfs2_io_error_bh(sdp, bh);
-
list_move(&bd->bd_ail_st_list, &ai->ai_ail2_list);
}
- return list_empty(&ai->ai_ail1_list);
}
-static void gfs2_ail1_start(struct gfs2_sbd *sdp)
-{
- struct list_head *head;
- u64 sync_gen;
- struct gfs2_ail *ai;
- int done = 0;
+/**
+ * gfs2_ail1_empty - Try to empty the ail1 lists
+ * @sdp: The superblock
+ *
+ * Tries to empty the ail1 lists, starting with the oldest first
+ */
- spin_lock(&sdp->sd_ail_lock);
- head = &sdp->sd_ail1_list;
- if (list_empty(head)) {
- spin_unlock(&sdp->sd_ail_lock);
- return;
- }
- sync_gen = sdp->sd_ail_sync_gen++;
-
- while(!done) {
- done = 1;
- list_for_each_entry_reverse(ai, head, ai_list) {
- if (ai->ai_sync_gen >= sync_gen)
- continue;
- ai->ai_sync_gen = sync_gen;
- gfs2_ail1_start_one(sdp, ai); /* This may drop ail lock */
- done = 0;
- break;
- }
- }
-
- spin_unlock(&sdp->sd_ail_lock);
-}
-
-static int gfs2_ail1_empty(struct gfs2_sbd *sdp, int flags)
+static int gfs2_ail1_empty(struct gfs2_sbd *sdp)
{
struct gfs2_ail *ai, *s;
int ret;
spin_lock(&sdp->sd_ail_lock);
-
list_for_each_entry_safe_reverse(ai, s, &sdp->sd_ail1_list, ai_list) {
- if (gfs2_ail1_empty_one(sdp, ai, flags))
+ gfs2_ail1_empty_one(sdp, ai);
+ if (list_empty(&ai->ai_ail1_list))
list_move(&ai->ai_list, &sdp->sd_ail2_list);
- else if (!(flags & DIO_ALL))
+ else
break;
}
-
ret = list_empty(&sdp->sd_ail1_list);
-
spin_unlock(&sdp->sd_ail_lock);
return ret;
@@ -569,7 +576,7 @@
set_buffer_uptodate(bh);
clear_buffer_dirty(bh);
- gfs2_ail1_empty(sdp, 0);
+ gfs2_ail1_empty(sdp);
tail = current_tail(sdp);
lh = (struct gfs2_log_header *)bh->b_data;
@@ -864,7 +871,7 @@
gfs2_log_flush(sdp, NULL);
for (;;) {
gfs2_ail1_start(sdp);
- if (gfs2_ail1_empty(sdp, DIO_ALL))
+ if (gfs2_ail1_empty(sdp))
break;
msleep(10);
}
@@ -900,17 +907,15 @@
preflush = atomic_read(&sdp->sd_log_pinned);
if (gfs2_jrnl_flush_reqd(sdp) || t == 0) {
- gfs2_ail1_empty(sdp, DIO_ALL);
+ gfs2_ail1_empty(sdp);
gfs2_log_flush(sdp, NULL);
- gfs2_ail1_empty(sdp, DIO_ALL);
}
if (gfs2_ail_flush_reqd(sdp)) {
gfs2_ail1_start(sdp);
io_schedule();
- gfs2_ail1_empty(sdp, 0);
+ gfs2_ail1_empty(sdp);
gfs2_log_flush(sdp, NULL);
- gfs2_ail1_empty(sdp, DIO_ALL);
}
wake_up(&sdp->sd_log_waitq);