/**
* bdi_start_writeback - start writeback
* @bdi: the backing device to write from
- * @sb: write inodes from this super_block
* @nr_pages: the number of pages to write
*
* Description:
* completion. Caller need not hold sb s_umount semaphore.
*
*/
-void bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb,
- long nr_pages)
+void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages)
{
struct wb_writeback_args args = {
- .sb = sb,
.sync_mode = WB_SYNC_NONE,
.nr_pages = nr_pages,
.range_cyclic = 1,
};
- /*
- * We treat @nr_pages=0 as the special case to do background writeback,
- * ie. to sync pages until the background dirty threshold is reached.
- */
- if (!nr_pages) {
- args.nr_pages = LONG_MAX;
- args.for_background = 1;
- }
+ bdi_alloc_queue_work(bdi, &args);
+}
+/**
+ * bdi_start_background_writeback - start background writeback
+ * @bdi: the backing device to write from
+ *
+ * Description:
+ * This does WB_SYNC_NONE background writeback. The IO is only
+ * started when this function returns, we make no guarentees on
+ * completion. Caller need not hold sb s_umount semaphore.
+ */
+void bdi_start_background_writeback(struct backing_dev_info *bdi)
+{
+ struct wb_writeback_args args = {
+ .sync_mode = WB_SYNC_NONE,
+ .nr_pages = LONG_MAX,
+ .for_background = 1,
+ .range_cyclic = 1,
+ };
bdi_alloc_queue_work(bdi, &args);
}
return ret;
}
-static void unpin_sb_for_writeback(struct super_block *sb)
-{
- up_read(&sb->s_umount);
- put_super(sb);
-}
-
-enum sb_pin_state {
- SB_PINNED,
- SB_NOT_PINNED,
- SB_PIN_FAILED
-};
-
/*
- * For WB_SYNC_NONE writeback, the caller does not have the sb pinned
+ * For background writeback the caller does not have the sb pinned
* before calling writeback. So make sure that we do pin it, so it doesn't
* go away while we are writing inodes from it.
*/
-static enum sb_pin_state pin_sb_for_writeback(struct writeback_control *wbc,
- struct super_block *sb)
+static bool pin_sb_for_writeback(struct super_block *sb)
{
- /*
- * Caller must already hold the ref for this
- */
- if (wbc->sync_mode == WB_SYNC_ALL) {
- WARN_ON(!rwsem_is_locked(&sb->s_umount));
- return SB_NOT_PINNED;
- }
spin_lock(&sb_lock);
+ if (list_empty(&sb->s_instances)) {
+ spin_unlock(&sb_lock);
+ return false;
+ }
+
sb->s_count++;
+ spin_unlock(&sb_lock);
+
if (down_read_trylock(&sb->s_umount)) {
- if (sb->s_root) {
- spin_unlock(&sb_lock);
- return SB_PINNED;
- }
- /*
- * umounted, drop rwsem again and fall through to failure
- */
+ if (sb->s_root)
+ return true;
up_read(&sb->s_umount);
}
- sb->s_count--;
- spin_unlock(&sb_lock);
- return SB_PIN_FAILED;
+
+ put_super(sb);
+ return false;
}
/*
struct inode *inode = list_entry(wb->b_io.prev,
struct inode, i_list);
struct super_block *sb = inode->i_sb;
- enum sb_pin_state state;
- if (wbc->sb && sb != wbc->sb) {
- /* super block given and doesn't
- match, skip this inode */
- redirty_tail(inode);
- continue;
- }
- state = pin_sb_for_writeback(wbc, sb);
+ if (wbc->sb) {
+ /*
+ * We are requested to write out inodes for a specific
+ * superblock. This means we already have s_umount
+ * taken by the caller which also waits for us to
+ * complete the writeout.
+ */
+ if (sb != wbc->sb) {
+ redirty_tail(inode);
+ continue;
+ }
- if (state == SB_PIN_FAILED) {
- requeue_io(inode);
- continue;
+ WARN_ON(!rwsem_is_locked(&sb->s_umount));
+
+ ret = writeback_sb_inodes(sb, wb, wbc);
+ } else {
+ if (!pin_sb_for_writeback(sb)) {
+ requeue_io(inode);
+ continue;
+ }
+ ret = writeback_sb_inodes(sb, wb, wbc);
+ drop_super(sb);
}
- ret = writeback_sb_inodes(sb, wb, wbc);
- if (state == SB_PINNED)
- unpin_sb_for_writeback(sb);
if (ret)
break;
}
}
/*
- * Schedule writeback for all backing devices. This does WB_SYNC_NONE
- * writeback, for integrity writeback see bdi_queue_work_onstack().
+ * Start writeback of `nr_pages' pages. If `nr_pages' is zero, write back
+ * the whole world.
*/
-static void bdi_writeback_all(struct super_block *sb, long nr_pages)
+void wakeup_flusher_threads(long nr_pages)
{
+ struct backing_dev_info *bdi;
struct wb_writeback_args args = {
- .sb = sb,
- .nr_pages = nr_pages,
.sync_mode = WB_SYNC_NONE,
};
- struct backing_dev_info *bdi;
- rcu_read_lock();
+ if (nr_pages) {
+ args.nr_pages = nr_pages;
+ } else {
+ args.nr_pages = global_page_state(NR_FILE_DIRTY) +
+ global_page_state(NR_UNSTABLE_NFS);
+ }
+ rcu_read_lock();
list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) {
if (!bdi_has_dirty_io(bdi))
continue;
-
bdi_alloc_queue_work(bdi, &args);
}
-
rcu_read_unlock();
}
-/*
- * Start writeback of `nr_pages' pages. If `nr_pages' is zero, write back
- * the whole world.
- */
-void wakeup_flusher_threads(long nr_pages)
-{
- if (nr_pages == 0)
- nr_pages = global_page_state(NR_FILE_DIRTY) +
- global_page_state(NR_UNSTABLE_NFS);
- bdi_writeback_all(NULL, nr_pages);
-}
-
static noinline void block_dump___mark_inode_dirty(struct inode *inode)
{
if (inode->i_ino || strcmp(inode->i_sb->s_id, "bdev")) {
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