On Wed, 2009-07-22 at 22:05 -0500, Eric Sandeen wrote: > Frank Mayhar wrote: > > On Tue, 2009-07-21 at 15:54 -0600, Andreas Dilger wrote: > > ... > > >> That said, we might need to have some kind of flag in the on-disk > >> inode to indicate that it was preallocated beyond EOF. Otherwise, > >> e2fsck will try and extend the file size to match the block count, > >> which isn't correct. We could also use this flag to determine if > >> truncate needs to be run on the inode even if the new size is the > >> same. > > > > After chatting with Curt about this today, it sounds like this needs two > > things. One is your flag in the on-disk inode, set in fallocate() to > > indicate that it has an allocation past EOF. E2fsck would use this to > > avoid "fixing" the file size to match the block count. Truncate would > > use this to notice that there are blocks allocated past i_size and get > > rid of them. It would be cleared by truncate or by ext4_get_blocks when > > using the last block of such an allocation. > > > > Does this make sense? Have I missed anything? > > I guess I'm not totally sold on the new on-disk flag; we can work out > blocks past EOF w/o needing a new flag can't we? It's on-disk because e2fsck needs it to know when not to extend i_size to the actual allocated length of the file. Were it not for that we could easily solve the fallocate/trucate problem with an in-memory flag only. -- Frank Mayhar <fmayhar@xxxxxxxxxx> Google, Inc. -- 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
