3015196746
This commit adds XFS_ERRTAG_BMAP_ALLOC_MINLEN_EXTENT error tag which helps userspace test programs to get xfs_bmap_btalloc() to always allocate minlen sized extents. This is required for test programs which need a guarantee that minlen extents allocated for a file do not get merged with their existing neighbours in the inode's BMBT. "Inode fork extent overflow check" for Directories, Xattrs and extension of realtime inodes need this since the file offset at which the extents are being allocated cannot be explicitly controlled from userspace. One way to use this error tag is to, 1. Consume all of the free space by sequentially writing to a file. 2. Punch alternate blocks of the file. This causes CNTBT to contain sufficient number of one block sized extent records. 3. Inject XFS_ERRTAG_BMAP_ALLOC_MINLEN_EXTENT error tag. After step 3, xfs_bmap_btalloc() will issue space allocation requests for minlen sized extents only. ENOSPC error code is returned to userspace when there aren't any "one block sized" extents left in any of the AGs. Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Chandan Babu R <chandanrlinux@gmail.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.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.