From 5a3e5cb8e08bd876e2542c1451c9a93dab1b0e39 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Mon, 27 Apr 2009 16:43:48 +0200 Subject: vfs: Fix sys_sync() and fsync_super() reliability (version 4) So far, do_sync() called: sync_inodes(0); sync_supers(); sync_filesystems(0); sync_filesystems(1); sync_inodes(1); This ordering makes it kind of hard for filesystems as sync_inodes(0) need not submit all the IO (for example it skips inodes with I_SYNC set) so e.g. forcing transaction to disk in ->sync_fs() is not really enough. Therefore sys_sync has not been completely reliable on some filesystems (ext3, ext4, reiserfs, ocfs2 and others are hit by this) when racing e.g. with background writeback. A similar problem hits also other filesystems (e.g. ext2) because of write_supers() being called before the sync_inodes(1). Change the ordering of calls in do_sync() - this requires a new function sync_blockdevs() to preserve the property that block devices are always synced after write_super() / sync_fs() call. The same issue is fixed in __fsync_super() function used on umount / remount read-only. [AV: build fixes] Signed-off-by: Jan Kara Signed-off-by: Al Viro --- fs/sync.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'fs/sync.c') diff --git a/fs/sync.c b/fs/sync.c index 7abc65fbf21..631fd5aece7 100644 --- a/fs/sync.c +++ b/fs/sync.c @@ -13,6 +13,7 @@ #include #include #include +#include "internal.h" #define VALID_FLAGS (SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE| \ SYNC_FILE_RANGE_WAIT_AFTER) @@ -26,10 +27,11 @@ static void do_sync(unsigned long wait) wakeup_pdflush(0); sync_inodes(0); /* All mappings, inodes and their blockdevs */ vfs_dq_sync(NULL); + sync_inodes(wait); /* Mappings, inodes and blockdevs, again. */ 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. */ + sync_blockdevs(); if (!wait) printk("Emergency Sync complete\n"); if (unlikely(laptop_mode)) -- cgit v1.2.3