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The name ATA_QCFLAG_FAILED is misleading since it does not mean that a QC completed in error, or that it didn't complete at all. It means that libata decided to schedule EH for the QC, so the QC is now owned by the libata error handler (EH). The normal execution path is responsible for not accessing a QC owned by EH. libata core enforces the rule by returning NULL from ata_qc_from_tag() for QCs owned by EH. It is quite easy to mistake that a QC marked with ATA_QCFLAG_FAILED was an error. However, a QC that was actually an error is instead indicated by having qc->err_mask set. E.g. when we have a NCQ error, we abort all QCs, which currently will mark all QCs as ATA_QCFLAG_FAILED. However, it will only be a single QC that is an error (i.e. has qc->err_mask set). Rename ATA_QCFLAG_FAILED to ATA_QCFLAG_EH to more clearly highlight that this flag simply means that a QC is now owned by EH. This new name will not mislead to think that the QC was an error (which is instead indicated by having qc->err_mask set). This also makes it more obvious that the EH code skips all QCs that do not have ATA_QCFLAG_EH set (rather than ATA_QCFLAG_FAILED), since the EH code should simply only care about QCs that are owned by EH itself. Signed-off-by: Niklas Cassel <niklas.cassel@wdc.com> Reviewed-by: John Garry <john.g.garry@oracle.com> Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.