Messages in this thread | | | Date | Fri, 6 Oct 2006 23:06:09 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH 0/3] Fix IO error reporting on fsync() |
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On Fri, 6 Oct 2006 13:49:47 +0200 Jan Kara <jack@suse.cz> wrote:
> current code in buffer.c has two pitfalls that cause problems with IO > error reporting of filesystems using mapping->private_list for their > metadata buffers (e.g. ext2). > The first problem is that end_io_async_write() does not mark IO error > in the buffer flags, only in the page flags. Hence fsync_buffers_list() > does not find out that some IO error has occured and will not report it. > The second problem is that buffers from private_list can be freed > (e.g. under memory pressure) and if fsync_buffer_list() is called after > that moment, IO error is lost - note that metadata buffers mark AS_EIO > on the *device mapping* not on the inode mapping. > Following series of three patches tries to fix these problems. The > approach I took (after some discussions with Andrew) is introducing > dummy buffer_head in the mapping instead of private_list. This dummy > buffer head serves as a head of metadata buffer list and also collects > IO errors from other buffers on the list (see the third patch for more > details). This is kind of compromise between introducing a pointer to > inode's address_space into each buffer and between using list_head > instead of buffer_head and playing some dirty tricks to recognize that > one particular list_head is actually from address_space and not from > buffer_head. Any suggestions for improvements welcome.
This is really complex, and enlarges the inode by quite a lot, which hurts.
What about putting an address_space* into the buffer_head? Transfer the EIO state into the address_space within, say, __remove_assoc_queue()? - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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