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PNFS block/SCSI layouts should gracefully handle cases where block devices are not available when a layout is retrieved, or the block devices are removed while the client holds a layout. While setting up a layout segment, keep a record of an unavailable or un-parsable block device in cache with a flag so that subsequent layouts do not spam the server with GETDEVINFO. We can reuse the current NFS_DEVICEID_UNAVAILABLE handling with one variation: instead of reusing the device, we will discard it and send a fresh GETDEVINFO after the timeout, since the lookup and validation of the device occurs within the GETDEVINFO response handling. A lookup of a layout segment that references an unavailable device will return a segment with the NFS_LSEG_UNAVAILABLE flag set. This will allow the pgio layer to mark the layout with the appropriate fail bit, which forces subsequent IO to the MDS, and prevents spamming the server with LAYOUTGET, LAYOUTRETURN. Finally, when IO to a block device fails, look up the block device(s) referenced by the pgio header, and mark them as unavailable. Signed-off-by: Benjamin Coddington <bcodding@redhat.com> Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.