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    SubjectRe: [Patch][RFC] Supress Buffer I/O errors when SCSI REQ_QUIET flag set
    On Mon, Nov 24 2008, Keith Mannthey wrote:
    > Allow the scsi request REQ_QUIET flag to be propagated to the buffer
    > file system layer. The basic ideas is to pass the flag from the scsi
    > request to the bio (block IO) and then to the buffer layer. The buffer
    > layer can then suppress needless printks.
    >
    > This patch declutters the kernel log by removed the 40-50 (per lun)
    > buffer io error messages seen during a boot in my multipath setup . It
    > is a good chance any real errors will be missed in the "noise" it the
    > logs without this patch.
    >
    > During boot I see blocks of messages like
    > "
    > __ratelimit: 211 callbacks suppressed
    > Buffer I/O error on device sdm, logical block 5242879
    > Buffer I/O error on device sdm, logical block 5242879
    > Buffer I/O error on device sdm, logical block 5242847
    > Buffer I/O error on device sdm, logical block 1
    > Buffer I/O error on device sdm, logical block 5242878
    > Buffer I/O error on device sdm, logical block 5242879
    > Buffer I/O error on device sdm, logical block 5242879
    > Buffer I/O error on device sdm, logical block 5242879
    > Buffer I/O error on device sdm, logical block 5242879
    > Buffer I/O error on device sdm, logical block 5242872
    > "
    > in my logs.
    >
    > My disk environment is multipath fiber channel using the SCSI_DH_RDAC
    > code and multipathd. This topology includes an "active" and "ghost"
    > path for each lun. IO's to the "ghost" path will never complete and the
    > SCSI layer, via the scsi device handler rdac code, quick returns the IOs
    > to theses paths and sets the REQ_QUIET scsi flag to suppress the scsi
    > layer messages.
    >
    > I am wanting to extend the QUIET behavior to include the buffer file
    > system layer to deal with these errors as well. I have been running this
    > patch for a while now on several boxes without issue. A few runs of
    > bonnie++ show no noticeable difference in performance in my setup.
    >
    > Thanks for John Stultz for the quiet_error finalization.

    Looks good to me. I'll merge it up for 2.6.29.

    --
    Jens Axboe



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