diff options
Diffstat (limited to 'fs/btrfs')
| -rw-r--r-- | fs/btrfs/inode.c | 48 |
1 files changed, 44 insertions, 4 deletions
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 0276fa951641..28e0ad1478c3 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -489,9 +489,6 @@ static noinline int add_async_extent(struct async_chunk *cow, */ static inline bool inode_can_compress(struct btrfs_inode *inode) { - /* Subpage doesn't support compression yet */ - if (inode->root->fs_info->sectorsize < PAGE_SIZE) - return false; if (inode->flags & BTRFS_INODE_NODATACOW || inode->flags & BTRFS_INODE_NODATASUM) return false; @@ -513,6 +510,38 @@ static inline int inode_need_compress(struct btrfs_inode *inode, u64 start, btrfs_ino(inode)); return 0; } + /* + * Special check for subpage. + * + * We lock the full page then run each delalloc range in the page, thus + * for the following case, we will hit some subpage specific corner case: + * + * 0 32K 64K + * | |///////| |///////| + * \- A \- B + * + * In above case, both range A and range B will try to unlock the full + * page [0, 64K), causing the one finished later will have page + * unlocked already, triggering various page lock requirement BUG_ON()s. + * + * So here we add an artificial limit that subpage compression can only + * if the range is fully page aligned. + * + * In theory we only need to ensure the first page is fully covered, but + * the tailing partial page will be locked until the full compression + * finishes, delaying the write of other range. + * + * TODO: Make btrfs_run_delalloc_range() to lock all delalloc range + * first to prevent any submitted async extent to unlock the full page. + * By this, we can ensure for subpage case that only the last async_cow + * will unlock the full page. + */ + if (fs_info->sectorsize < PAGE_SIZE) { + if (!IS_ALIGNED(start, PAGE_SIZE) || + !IS_ALIGNED(end + 1, PAGE_SIZE)) + return 0; + } + /* force compress */ if (btrfs_test_opt(fs_info, FORCE_COMPRESS)) return 1; @@ -614,13 +643,24 @@ again: total_compressed = actual_end - start; /* - * skip compression for a small file range(<=blocksize) that + * Skip compression for a small file range(<=blocksize) that * isn't an inline extent, since it doesn't save disk space at all. */ if (total_compressed <= blocksize && (start > 0 || end + 1 < BTRFS_I(inode)->disk_i_size)) goto cleanup_and_bail_uncompressed; + /* + * For subpage case, we require full page alignment for the sector + * aligned range. + * Thus we must also check against @actual_end, not just @end. + */ + if (blocksize < PAGE_SIZE) { + if (!IS_ALIGNED(start, PAGE_SIZE) || + !IS_ALIGNED(round_up(actual_end, blocksize), PAGE_SIZE)) + goto cleanup_and_bail_uncompressed; + } + total_compressed = min_t(unsigned long, total_compressed, BTRFS_MAX_UNCOMPRESSED); total_in = 0; |