Btrfs assumes block size to be the same as the machine's page size. This would mean that a Btrfs instance created on a 4k page size machine (e.g. x86) will not be mountable on machines with larger page sizes (e.g. PPC64/AARCH64). This patchset aims to resolve this incompatibility.
This patchset continues with the work posted previously at http://marc.info/?l=linux-btrfs&m=146760691422240&w=2 This patchset is based on top of Josef's 1. Metadata throttling in writeback patches 2. Kill the btree inode patches The major change in this version is the usage of kmalloc()-ed memory for holding metadata blocks whose size is less than the machine's page size. This vastly reduces the complexity of extent buffer mangement (Thanks to Josef's "Kill the btree inode patches"). When writing back dirty extent buffers, we currently track the corresponding extent buffers using the pointer at page->private. With kmalloc-ed() memory this isn't possible and hence we track the first extent buffer under writeback using bio->bi_private. Also, For kmalloc-ed() extent buffers this patchset currently limits the number of dirty extent buffers in a "write" bio to 1. This limit will be removed in a future patchset. The commits for the Btrfs kernel module can be found at https://github.com/chandanr/linux/tree/btrfs/subpagesize-blocksize. To create a filesystem with block size < page size, a patched version of the Btrfs-progs package is required. The corresponding fixes for Btrfs-progs can be found at https://github.com/chandanr/btrfs-progs/tree/btrfs/subpagesize-blocksize. Fstests run status: 1. x86_64 - With 4k sectorsize, all the tests that succeed with the for-linus-4.8 branch at git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs.git branch also do so with the patches applied. 2. ppc64 - With 4k sectorsize, 16k nodesize and with "nospace_cache" mount option, except for scrub and compression tests, all the tests that succeed with the for-next branch at git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux.git branch also do so with the patches applied. - With 64k sectorsize & nodesize, all the tests that succeed with the for-linus-4.8 branch at git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs.git branch also do so with the patches applied. TODO: 1. On ppc64, btrfsck segfaults when checking a filesystem instance having 2k sectorsize. 2. I am planning to fix scrub & compression via a separate patchset. Changes from V20: 1. Applied all the review comments suggested by Josef for version V20. However, There are still some instances of if (compare_sectorsize_with_page_size) /* do something */ One such instance is in check_page_uptodate() where we would need to check for BLK_STATE_UPTODATE only if page_size < sectorsize. For page_size == sectorsize case, we unconditionally set PG_uptodate flag. Changes from V19: 1. The patchset has been rebased on top of kdave/for-next branch. 2. The patch "Btrfs: subpage-blocksize: extent_clear_unlock_delalloc: Prevent page from being unlocked more than once" changes the signatures of the functions "cow_file_range" & "extent_clear_unlock_delalloc". This patch has now been moved to be the first patch in the patchset. 3. A new patch "Btrfs: subpage-blocksize: Rate limit scrub error message" has been added. btrfs/073 invokes the scrub ioctl in a tight loop. In subpage-blocksize scenario this results in a lot of "scrub: size assumption sectorsize != PAGE_SIZE" messages being printed on the console. Hence this patch rate limits such error messages. Changes from V18: 1. The per-page bitmap used to track the block status is now allocated from a slab cache. 2. The per-page bitmap is allocated and used only in cases where sectorsize < PAGE_SIZE. 3. The new patch "Btrfs: subpage-blocksize: Disable compression" disables compression in subpage-blocksize scenario. Changes from V17: 1. Due to mistakes made during git rebase operations, fixes ended up in incorrect patches. This patchset gets the fixes in the right patches. Changes from V16: 1. The V15 patchset consisted of patches obtained from an incorrect git branch. Apologies for the mistake. All the entries listed under "Changes from V15" hold good for V16. Changes from V15: 1. The invocation of cleancache_get_page() in __do_readpage() assumed blocksize to be same as PAGE_SIZE. We now invoke cleancache_get_page() only if blocksize is same as PAGE_SIZE. Thanks to David Sterba for pointing this out. 2. In __extent_writepage_io() we used to accumulate all the contiguous dirty blocks within the page before submitting the file offset range for I/O. In some cases this caused the bio to span across more than a stripe. For example, With 4k block size, 64K stripe size and 64K page size, assume - All the blocks mapped by the page are contiguous on the logical address space. - The first block of the page is mapped to the second block of the stripe. In such a scenario, we would add all the blocks of the page to bio. This would mean that we would overflow the stripe by one 4K block. Hence this patchset removes the optimization and invokes submit_extent_page() for every dirty 4K block. 3. The following patches are newly added: - Btrfs: subpage-blocksize: __btrfs_lookup_bio_sums: Set offset when moving to a new bio_vec - Btrfs: subpage-blocksize: Make file extent relocate code subpage blocksize aware - Btrfs: btrfs_clone: Flush dirty blocks of a page that do not map the clone range Changes from V14: 1. Fix usage of cleancache_get_page() in __do_readpage(). In filesystems which support subpage-blocksize scenario, a page can map one or more blocks. Hence cleancache_get_page() should be invoked only when the page maps a non-hole extent and block size being used is equal to the page size. Thanks to David Sterba for pointing this out. 2. Replace page_read_complete() and page_write_complete() functions with page_io_complete(). 3. Provide more documentation (as part of both commit message and code comments) about the usage of the per-page btrfs_page_private->io_lock. Changes from V13: 1. Enable dedup ioctl to work in subpagesize-blocksize scenario. Changes from V12: 1. The logic in the function btrfs_punch_hole() has been fixed to check for the presence of BLK_STATE_UPTODATE flags for blocks in pages which partially map the file range being punched. Changes from V11: 1. Addressed the review comments provided by Liu Bo for version V11. 2. Fixed file defragmentation code to work in subpagesize-blocksize scenario. 3. Many "hard to reproduce" bugs were fixed. Chandan Rajendra (19): Btrfs: subpage-blocksize: extent_clear_unlock_delalloc: Prevent page from being unlocked more than once Btrfs: subpage-blocksize: Make sure delalloc range intersects with the locked page's range Btrfs: subpage-blocksize: Use PG_Uptodate flag to track block uptodate status Btrfs: Remove extent_io_tree's track_uptodate member Btrfs: subpage-blocksize: Fix whole page read. Btrfs: subpage-blocksize: Fix whole page write Btrfs: subpage-blocksize: Use kmalloc()-ed memory to hold metadata blocks Btrfs: subpage-blocksize: Execute sanity tests on all possible block sizes Btrfs: subpage-blocksize: Compute free space tree BITMAP_RANGE based on sectorsize Btrfs: subpage-blocksize: Allow mounting filesystems where sectorsize < PAGE_SIZE Btrfs: subpage-blocksize: Deal with partial ordered extent allocations. Btrfs: subpage-blocksize: Explicitly track I/O status of blocks of an ordered extent. Btrfs: subpage-blocksize: btrfs_punch_hole: Fix uptodate blocks check Btrfs: subpage-blocksize: Fix file defragmentation code Btrfs: subpage-blocksize: Enable dedupe ioctl Btrfs: subpage-blocksize: btrfs_clone: Flush dirty blocks of a page that do not map the clone range Btrfs: subpage-blocksize: Make file extent relocate code subpage blocksize aware Btrfs: subpage-blocksize: __btrfs_lookup_bio_sums: Set offset when moving to a new bio_vec Btrfs: subpage-blocksize: Disable compression fs/btrfs/ctree.h | 6 +- fs/btrfs/disk-io.c | 49 +-- fs/btrfs/disk-io.h | 2 +- fs/btrfs/extent-tree.c | 4 +- fs/btrfs/extent_io.c | 739 +++++++++++++++++++++------------ fs/btrfs/extent_io.h | 99 ++++- fs/btrfs/file-item.c | 7 +- fs/btrfs/file.c | 105 ++++- fs/btrfs/inode.c | 472 +++++++++++++++------ fs/btrfs/ioctl.c | 232 +++++++---- fs/btrfs/ordered-data.c | 19 + fs/btrfs/ordered-data.h | 4 + fs/btrfs/relocation.c | 87 +++- fs/btrfs/super.c | 19 + fs/btrfs/tests/btrfs-tests.c | 8 +- fs/btrfs/tests/extent-io-tests.c | 4 +- fs/btrfs/tests/free-space-tree-tests.c | 79 ++-- fs/btrfs/tree-log.c | 2 +- fs/btrfs/volumes.c | 10 +- 19 files changed, 1373 insertions(+), 574 deletions(-) -- 2.5.5 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
