Re: [RFC][PATCH] Possible data integrity problems in lots of filesystems?
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On 11/25/2010 12:06 PM, Nick Piggin wrote: > On Thu, Nov 25, 2010 at 11:28:14AM +0200, Boaz Harrosh wrote: >>> Index: linux-2.6/fs/exofs/file.c >>> =================================================================== >>> --- linux-2.6.orig/fs/exofs/file.c 2010-11-19 16:50:00.000000000 +1100 >>> +++ linux-2.6/fs/exofs/file.c 2010-11-19 16:50:07.000000000 +1100 >>> @@ -48,11 +48,6 @@ static int exofs_file_fsync(struct file >>> struct inode *inode = filp->f_mapping->host; >>> struct super_block *sb; >>> >>> - if (!(inode->i_state & I_DIRTY)) >>> - return 0; >>> - if (datasync && !(inode->i_state & I_DIRTY_DATASYNC)) >>> - return 0; >>> - >>> ret = sync_inode_metadata(inode, 1); >>> >>> /* This is a good place to write the sb */ >>> >> >> Is that a good enough fix for the issue in your opinion? >> Or is there more involved? > > For the inode dirty bit race problem, yes it should fix it. > sync_inode_metadata basically makes the same checks without > races (in a subsequent patch I re-introduced the datasync > optimisation). > > > > Well in your fsync, you need to wait for inode writeback > that might have been started by an asynchronous write_inode. > All I'm calling is sync_inode_metadata(,1) which calls sync_inode() which calls writeback_single_inode(sync_mode == WB_SYNC_ALL). It gets a little complicated but from the looks of it, even though the call to .write_inode() is not under any lock the state machine there will do inode_wait_for_writeback() if there was one in motion all ready. ? And it looks like writeback_single_inode() does all the proper checks in the correct order for these flags above. So current code in exofs_file_fsync() looks scary to me. I would like to push your above patch for this Kernel. (I'll repost it) > Also, with your sync_inode_metadata call, you shouldn't need the > sync_inode call by the looks. > What? I missed you. You mean I don't need to sync_inode_metadata(,wait==1), or what did you mean? > Thanks, > Nick > Thanks Boaz -- To unsubscribe from this list: send the line "unsubscribe reiserfs-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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