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-rw-r--r--fs/sync.c117
1 files changed, 100 insertions, 17 deletions
diff --git a/fs/sync.c b/fs/sync.c
index 7abc65f..dd20002 100644
--- a/fs/sync.c
+++ b/fs/sync.c
@@ -13,38 +13,123 @@
#include <linux/pagemap.h>
#include <linux/quotaops.h>
#include <linux/buffer_head.h>
+#include "internal.h"
#define VALID_FLAGS (SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE| \
SYNC_FILE_RANGE_WAIT_AFTER)
/*
- * sync everything. Start out by waking pdflush, because that writes back
- * all queues in parallel.
+ * Do the filesystem syncing work. For simple filesystems sync_inodes_sb(sb, 0)
+ * just dirties buffers with inodes so we have to submit IO for these buffers
+ * via __sync_blockdev(). This also speeds up the wait == 1 case since in that
+ * case write_inode() functions do sync_dirty_buffer() and thus effectively
+ * write one block at a time.
*/
-static void do_sync(unsigned long wait)
+static int __sync_filesystem(struct super_block *sb, int wait)
{
- wakeup_pdflush(0);
- sync_inodes(0); /* All mappings, inodes and their blockdevs */
- vfs_dq_sync(NULL);
- sync_supers(); /* Write the superblocks */
- sync_filesystems(0); /* Start syncing the filesystems */
- sync_filesystems(wait); /* Waitingly sync the filesystems */
- sync_inodes(wait); /* Mappings, inodes and blockdevs, again. */
+ /* Avoid doing twice syncing and cache pruning for quota sync */
if (!wait)
- printk("Emergency Sync complete\n");
- if (unlikely(laptop_mode))
- laptop_sync_completion();
+ writeout_quota_sb(sb, -1);
+ else
+ sync_quota_sb(sb, -1);
+ sync_inodes_sb(sb, wait);
+ if (sb->s_op->sync_fs)
+ sb->s_op->sync_fs(sb, wait);
+ return __sync_blockdev(sb->s_bdev, wait);
+}
+
+/*
+ * Write out and wait upon all dirty data associated with this
+ * superblock. Filesystem data as well as the underlying block
+ * device. Takes the superblock lock.
+ */
+int sync_filesystem(struct super_block *sb)
+{
+ int ret;
+
+ /*
+ * We need to be protected against the filesystem going from
+ * r/o to r/w or vice versa.
+ */
+ WARN_ON(!rwsem_is_locked(&sb->s_umount));
+
+ /*
+ * No point in syncing out anything if the filesystem is read-only.
+ */
+ if (sb->s_flags & MS_RDONLY)
+ return 0;
+
+ ret = __sync_filesystem(sb, 0);
+ if (ret < 0)
+ return ret;
+ return __sync_filesystem(sb, 1);
+}
+EXPORT_SYMBOL_GPL(sync_filesystem);
+
+/*
+ * Sync all the data for all the filesystems (called by sys_sync() and
+ * emergency sync)
+ *
+ * This operation is careful to avoid the livelock which could easily happen
+ * if two or more filesystems are being continuously dirtied. s_need_sync
+ * is used only here. We set it against all filesystems and then clear it as
+ * we sync them. So redirtied filesystems are skipped.
+ *
+ * But if process A is currently running sync_filesystems and then process B
+ * calls sync_filesystems as well, process B will set all the s_need_sync
+ * flags again, which will cause process A to resync everything. Fix that with
+ * a local mutex.
+ */
+static void sync_filesystems(int wait)
+{
+ struct super_block *sb;
+ static DEFINE_MUTEX(mutex);
+
+ mutex_lock(&mutex); /* Could be down_interruptible */
+ spin_lock(&sb_lock);
+ list_for_each_entry(sb, &super_blocks, s_list)
+ sb->s_need_sync = 1;
+
+restart:
+ list_for_each_entry(sb, &super_blocks, s_list) {
+ if (!sb->s_need_sync)
+ continue;
+ sb->s_need_sync = 0;
+ sb->s_count++;
+ spin_unlock(&sb_lock);
+
+ down_read(&sb->s_umount);
+ if (!(sb->s_flags & MS_RDONLY) && sb->s_root)
+ __sync_filesystem(sb, wait);
+ up_read(&sb->s_umount);
+
+ /* restart only when sb is no longer on the list */
+ spin_lock(&sb_lock);
+ if (__put_super_and_need_restart(sb))
+ goto restart;
+ }
+ spin_unlock(&sb_lock);
+ mutex_unlock(&mutex);
}
SYSCALL_DEFINE0(sync)
{
- do_sync(1);
+ sync_filesystems(0);
+ sync_filesystems(1);
+ if (unlikely(laptop_mode))
+ laptop_sync_completion();
return 0;
}
static void do_sync_work(struct work_struct *work)
{
- do_sync(0);
+ /*
+ * Sync twice to reduce the possibility we skipped some inodes / pages
+ * because they were temporarily locked
+ */
+ sync_filesystems(0);
+ sync_filesystems(0);
+ printk("Emergency Sync complete\n");
kfree(work);
}
@@ -75,10 +160,8 @@ int file_fsync(struct file *filp, struct dentry *dentry, int datasync)
/* sync the superblock to buffers */
sb = inode->i_sb;
- lock_super(sb);
if (sb->s_dirt && sb->s_op->write_super)
sb->s_op->write_super(sb);
- unlock_super(sb);
/* .. finally sync the buffers to disk */
err = sync_blockdev(sb->s_bdev);
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