• David Chinner's avatar
    [XFS] Prevent ENOSPC from aborting transactions that need to succeed · 84e1e99f
    David Chinner authored
    During delayed allocation extent conversion or unwritten extent
    conversion, we need to reserve some blocks for transactions reservations.
    We need to reserve these blocks in case a btree split occurs and we need
    to allocate some blocks.
    
    Unfortunately, we've only ever reserved the number of data blocks we are
    allocating, so in both the unwritten and delalloc case we can get ENOSPC
    to the transaction reservation. This is bad because in both cases we
    cannot report the failure to the writing application.
    
    The fix is two-fold:
    
    1 - leverage the reserved block infrastructure XFS already
    has to reserve a small pool of blocks by default to allow
    specially marked transactions to dip into when we are at
    ENOSPC.
    Default setting is min(5%, 1024 blocks).
    
    2 - convert critical transaction reservations to be allowed
    to dip into this pool. Spots changed are delalloc
    conversion, unwritten extent conversion and growing a
    filesystem at ENOSPC.
    This also allows growing the filesytsem to succeed at ENOSPC.
    
    SGI-PV: 964468
    SGI-Modid: xfs-linux-melb:xfs-kern:28865a
    Signed-off-by: default avatarDavid Chinner <dgc@sgi.com>
    Signed-off-by: default avatarTim Shimmin <tes@sgi.com>
    84e1e99f
xfs_mount.c 62.9 KB