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    SubjectRe: lockdep: inconsistent {RECLAIM_FS-ON-W} -> {IN-RECLAIM_FS-R} usage.
    On Fri, Jan 15, 2010 at 01:53:15PM +0100, Peter Zijlstra wrote:
    > Well, I don't know enough about xfs (of filesystems in generic) to say
    > that with any certainty, but I can imagine inode writeback from the sync
    > that goes with umount to cause issues.
    > If this inode reclaim is past all that and the filesystem is basically
    > RO, then I don't think so and this could be considered a false positive,
    > in which case we need an annotation for this.

    The issue is a bit more complicated. In the unmount case
    invalidate_inodes() is indeed called after the filesystem is effectively
    read-only for user origination operations. But there's a miriad of
    other invalidate_inodes() calls:

    - fs/block_dev.c:__invalidate_device()

    This gets called from block device codes for various kinds of
    invalidations. Doesn't make any sense at all to me, but hey..

    - fs/ext2/super.c:ext2_remount()

    Appears like it's used to check for activate inodes during
    remount. Very fishy usage, and could just be replaced with
    a list walk without any I/O

    - fs/gfs2/glock.c:gfs2_gl_hash_clear()

    No idea.

    - fs/gfs2/ops_fstype.c:fill_super()

    Tries to kill all inodes in the fill_super error path, looks
    very fishy.

    - fs/ntfs/super.c:ntfs_fill_super()

    Failure case of fill_super again, does not look very useful.A

    - fs/smbfs/inode.c:smb_invalidate_inodes()

    Used when a connection goes bad.

    In short we can't generally rely on this only happening on a dead fs.

    But in the end we abuse iprune_sem to work around a ref counting
    problem. As long as we keep a reference to the superblock for each
    inode on the dispose list the superblock can't go away and there's
    no need for the lock at all.

     \ /
      Last update: 2010-01-19 19:49    [W:0.020 / U:14.564 seconds]
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