966d879baf
In the rework of btrfs_defrag_file(), we always call defrag_one_cluster() and increase the offset by cluster size, which is only 256K. But there are cases where we have a large extent (e.g. 128M) which doesn't need to be defragged at all. Before the refactor, we can directly skip the range, but now we have to scan that extent map again and again until the cluster moves after the non-target extent. Fix the problem by allow defrag_one_cluster() to increase btrfs_defrag_ctrl::last_scanned to the end of an extent, if and only if the last extent of the cluster is not a target. The test script looks like this: mkfs.btrfs -f $dev > /dev/null mount $dev $mnt # As btrfs ioctl uses 32M as extent_threshold xfs_io -f -c "pwrite 0 64M" $mnt/file1 sync # Some fragemented range to defrag xfs_io -s -c "pwrite 65548k 4k" \ -c "pwrite 65544k 4k" \ -c "pwrite 65540k 4k" \ -c "pwrite 65536k 4k" \ $mnt/file1 sync echo "=== before ===" xfs_io -c "fiemap -v" $mnt/file1 echo "=== after ===" btrfs fi defrag $mnt/file1 sync xfs_io -c "fiemap -v" $mnt/file1 umount $mnt With extra ftrace put into defrag_one_cluster(), before the patch it would result tons of loops: (As defrag_one_cluster() is inlined, the function name is its caller) btrfs-126062 [005] ..... 4682.816026: btrfs_defrag_file: r/i=5/257 start=0 len=262144 btrfs-126062 [005] ..... 4682.816027: btrfs_defrag_file: r/i=5/257 start=262144 len=262144 btrfs-126062 [005] ..... 4682.816028: btrfs_defrag_file: r/i=5/257 start=524288 len=262144 btrfs-126062 [005] ..... 4682.816028: btrfs_defrag_file: r/i=5/257 start=786432 len=262144 btrfs-126062 [005] ..... 4682.816028: btrfs_defrag_file: r/i=5/257 start=1048576 len=262144 ... btrfs-126062 [005] ..... 4682.816043: btrfs_defrag_file: r/i=5/257 start=67108864 len=262144 But with this patch there will be just one loop, then directly to the end of the extent: btrfs-130471 [014] ..... 5434.029558: defrag_one_cluster: r/i=5/257 start=0 len=262144 btrfs-130471 [014] ..... 5434.029559: defrag_one_cluster: r/i=5/257 start=67108864 len=16384 CC: stable@vger.kernel.org # 5.16 Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
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| LICENSES | ||
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
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| README | ||
README
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.