If filesystem was aborted after inode's write back is complete but before its metadata was updated we may return success results in data loss. In order to handle fs abort correctly we have to check fs state once we discover that it is in MS_RDONLY state Test case: http://patchwork.ozlabs.org/patch/244297 Changes from V1: - fix spelling Signed-off-by: Dmitry Monakhov <dmonakhov@xxxxxxxxxx> --- fs/ext4/fsync.c | 8 ++++++-- fs/ext4/super.c | 12 +++++++++++- 2 files changed, 17 insertions(+), 3 deletions(-) diff --git a/fs/ext4/fsync.c b/fs/ext4/fsync.c index e0ba8a4..d7df2f1 100644 --- a/fs/ext4/fsync.c +++ b/fs/ext4/fsync.c @@ -129,9 +129,13 @@ int ext4_sync_file(struct file *file, loff_t start, loff_t end, int datasync) return ret; mutex_lock(&inode->i_mutex); - if (inode->i_sb->s_flags & MS_RDONLY) + if (inode->i_sb->s_flags & MS_RDONLY) { + /* Make shure that we read updated s_mount_flags value */ + smp_rmb(); + if (EXT4_SB(inode->i_sb)->s_mount_flags & EXT4_MF_FS_ABORTED) + ret = -EROFS; goto out; - + } ret = ext4_flush_unwritten_io(inode); if (ret < 0) goto out; diff --git a/fs/ext4/super.c b/fs/ext4/super.c index edc716d..b4154d3 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -399,6 +399,11 @@ static void ext4_handle_error(struct super_block *sb) } if (test_opt(sb, ERRORS_RO)) { ext4_msg(sb, KERN_CRIT, "Remounting filesystem read-only"); + /* + * Make shure updated value of ->s_mount_flags will be visiable + * before ->s_flags update + */ + smp_wmb(); sb->s_flags |= MS_RDONLY; } if (test_opt(sb, ERRORS_PANIC)) @@ -571,8 +576,13 @@ void __ext4_abort(struct super_block *sb, const char *function, if ((sb->s_flags & MS_RDONLY) == 0) { ext4_msg(sb, KERN_CRIT, "Remounting filesystem read-only"); - sb->s_flags |= MS_RDONLY; EXT4_SB(sb)->s_mount_flags |= EXT4_MF_FS_ABORTED; + /* + * Make shure updated value of ->s_mount_flags will be visiable + * before ->s_flags update + */ + smp_wmb(); + sb->s_flags |= MS_RDONLY; if (EXT4_SB(sb)->s_journal) jbd2_journal_abort(EXT4_SB(sb)->s_journal, -EIO); save_error_info(sb, function, line); -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
