ext4 has taken the stance that, in the absence of a journal,
when an fsync/fdatasync of an inode is done, the parent
directory should be sync'ed if this inode entry is new.
ext4_sync_parent(), which implements this, does indeed sync
the dirent pages for parent directories, but it does not
sync the directory *inode*. This patch fixes this.
I tested this using a power fail test, which panics a
machine running a file server getting requests from a
client. Without this patch, on about every other test run,
the server is missing many, many files that had been synced.
With this patch, on > 6 runs, I see zero files being lost.
Signed-off-by: Curt Wohlgemuth <curtw@xxxxxxxxxx>
---
fs/ext4/fsync.c | 11 ++++++++++-
1 files changed, 10 insertions(+), 1 deletions(-)
diff --git a/fs/ext4/fsync.c b/fs/ext4/fsync.c
index 7f74019..a276348 100644
--- a/fs/ext4/fsync.c
+++ b/fs/ext4/fsync.c
@@ -128,6 +128,7 @@ extern int ext4_flush_completed_IO(struct inode *inode)
static void ext4_sync_parent(struct inode *inode)
{
struct dentry *dentry = NULL;
+ int ret;
while (inode && ext4_test_inode_state(inode, EXT4_STATE_NEWENTRY)) {
ext4_clear_inode_state(inode, EXT4_STATE_NEWENTRY);
@@ -136,7 +137,15 @@ static void ext4_sync_parent(struct inode *inode)
if (!dentry || !dentry->d_parent || !dentry->d_parent->d_inode)
break;
inode = dentry->d_parent->d_inode;
- sync_mapping_buffers(inode->i_mapping);
+ ret = sync_mapping_buffers(inode->i_mapping);
+ if (! ret) {
+ struct writeback_control wbc = {
+ .sync_mode = WB_SYNC_ALL,
+ .nr_to_write = 0, /* metadata-only; caller
+ takes care of data */
+ };
+ (void)sync_inode(inode, &wbc);
+ }
}
}
--
1.7.3.1
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