[PATCH 0/2] Fix IO error reporting on fsync() (2nd try)

[Jan Kara]

  Hello,

  Andrew felt the changes were too complex and increasing the size of
inodes too much. Here comes a new version of the patches

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 two patches tries to fix these problems. It adds a
pointer to each buffer head that point to the associated mapping in case
the buffer head is in the private_list. If a buffer is removed from
private_list, the IO error is transferred from a buffer to the
corresponding associated mapping.

								Honza

-- 
Jan Kara <jack@xxxxxxx>
SuSE CR Labs
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