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| author | Jan Kara <jack@suse.cz> | 2009-04-27 16:43:48 +0200 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2009-06-11 21:36:03 -0400 |
| commit | 5a3e5cb8e08bd876e2542c1451c9a93dab1b0e39 (patch) | |
| tree | 3b792d21246f1001adeca8b67df24ca71593dd3f /fs/sync.c | |
| parent | 876a9f76abbcb775f8d21cbc99fa161f9e5937f1 (diff) | |
| download | lwn-5a3e5cb8e08bd876e2542c1451c9a93dab1b0e39.tar.gz lwn-5a3e5cb8e08bd876e2542c1451c9a93dab1b0e39.zip | |
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 <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/sync.c')
| -rw-r--r-- | fs/sync.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/fs/sync.c b/fs/sync.c index 7abc65fbf21d..631fd5aece78 100644 --- a/fs/sync.c +++ b/fs/sync.c @@ -13,6 +13,7 @@ #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) @@ -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)) |