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Wed, 26 Aug 2026 15:56:39 -0700 (PDT) Received: from pop-os.attlocal.net ([2600:1700:6476:1430:6de1:2161:6e4f:d299]) by smtp.gmail.com with ESMTPSA id 956f58d0204a3-66d243b9d47sm2130161d50.0.2026.08.26.15.56.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 26 Aug 2026 15:56:39 -0700 (PDT) From: Viacheslav Dubeyko To: glaubitz@physik.fu-berlin.de, frank.li@vivo.com, hch@lst.de Cc: linux-fsdevel@vger.kernel.org, vdubeyko@coreweave.com, Viacheslav Dubeyko Subject: [PATCH v2 2/7] hfsplus: rework hfsplus_get_block() logic Date: Wed, 26 Aug 2026 15:56:09 -0700 Message-ID: <20260826225614.486112-3-slava@dubeyko.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260826225614.486112-1-slava@dubeyko.com> References: <20260826225614.486112-1-slava@dubeyko.com> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Split the extent-lookup/allocate logic out of hfsplus_get_block() into a new hfsplus_map_extent(), which reports the mapping as (dblock, max_blocks, balloc) instead of filling in a buffer_head. hfsplus_get_block() becomes a thin wrapper around it for the buffer_head-based callers (B-tree metadata, symlinks). No functional change to the existing buffer_head path. This is preparation for the iomap-based regular file I/O path added in a later patch, which will call hfsplus_map_extent() directly. cc: Christoph Hellwig cc: John Paul Adrian Glaubitz cc: Yangtao Li cc: linux-fsdevel@vger.kernel.org Reviewed-by: Christoph Hellwig Signed-off-by: Viacheslav Dubeyko --- fs/hfsplus/extents.c | 118 +++++++++++++++++++++++++++++----------- fs/hfsplus/hfsplus_fs.h | 2 + 2 files changed, 87 insertions(+), 33 deletions(-) diff --git a/fs/hfsplus/extents.c b/fs/hfsplus/extents.c index eb7c11524d18..ffd52ad8867c 100644 --- a/fs/hfsplus/extents.c +++ b/fs/hfsplus/extents.c @@ -48,18 +48,29 @@ static void hfsplus_ext_build_key(hfsplus_btree_key *key, u32 cnid, key->ext.pad = 0; } -static u32 hfsplus_ext_find_block(struct hfsplus_extent *ext, u32 off) +/* + * hfsplus_ext_find_block() - find contiguous sequence of block + * + * Find the disk allocation block for 'off' within an 8-entry + * extent record, and the number of further allocation blocks + * that are contiguous with it in the same extent entry. + */ +static u32 hfsplus_ext_find_block(struct hfsplus_extent *ext, u32 off, + u32 *dblock) { int i; u32 count; - for (i = 0; i < 8; ext++, i++) { + for (i = 0; i < HFSPLUS_FORK_EXTENT_COUNT; ext++, i++) { count = be32_to_cpu(ext->block_count); - if (off < count) - return be32_to_cpu(ext->start_block) + off; + if (off < count) { + *dblock = be32_to_cpu(ext->start_block) + off; + return count - off; + } off -= count; } /* panic? */ + *dblock = 0; return 0; } @@ -68,7 +79,7 @@ static int hfsplus_ext_block_count(struct hfsplus_extent *ext) int i; u32 count = 0; - for (i = 0; i < 8; ext++, i++) + for (i = 0; i < HFSPLUS_FORK_EXTENT_COUNT; ext++, i++) count += be32_to_cpu(ext->block_count); return count; } @@ -225,37 +236,46 @@ static int hfsplus_ext_read_extent(struct inode *inode, u32 block) return res; } -/* Get a block at iblock for inode, possibly allocating if create */ -int hfsplus_get_block(struct inode *inode, sector_t iblock, - struct buffer_head *bh_result, int create) +/* + * hfsplus_map_extent() - find or allocate a sequence of allocation blocks + * + * Looks up the allocation block at 'ablock' for inode, extending the + * file (via hfsplus_file_extend(), in clump_blocks-sized chunks) when + * 'create' is set and 'ablock' lies beyond the current allocation. + * + * On success, *dblock is the disk allocation block backing 'ablock', + * and *max_blocks is the number of further allocation blocks that are + * contiguous with it (i.e. the remaining length of the extent entry + * that contains 'ablock'), which may be smaller than the whole file's + * remaining allocation when the fork is fragmented across several + * extent entries. If a new extent had to be allocated to satisfy the + * request, *balloc (when non-NULL) is set to true. + */ +int hfsplus_map_extent(struct inode *inode, u32 ablock, int create, + u32 *dblock, u32 *max_blocks, bool *balloc) { - struct super_block *sb = inode->i_sb; - struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb); struct hfsplus_inode_info *hip = HFSPLUS_I(inode); - int res = -EIO; - u32 ablock, dblock, mask; - sector_t sector; - int was_dirty = 0; + int was_dirty; + int res; - /* Convert inode block to disk allocation block */ - ablock = iblock >> sbi->fs_shift; + if (balloc) + *balloc = false; - if (iblock >= hip->fs_blocks) { + if (ablock >= hip->alloc_blocks) { if (!create) - return 0; - if (iblock > hip->fs_blocks) return -EIO; - if (ablock >= hip->alloc_blocks) { - res = hfsplus_file_extend(inode, false); - if (res) - return res; - } - } else - create = 0; + res = hfsplus_file_extend(inode, false); + if (res) + return res; + if (balloc) + *balloc = true; + } if (ablock < hip->first_blocks) { - dblock = hfsplus_ext_find_block(hip->first_extents, ablock); - goto done; + *max_blocks = hfsplus_ext_find_block(hip->first_extents, + ablock, + dblock); + return 0; } if (inode->i_ino == HFSPLUS_EXT_CNID) @@ -274,11 +294,44 @@ int hfsplus_get_block(struct inode *inode, sector_t iblock, mutex_unlock(&hip->extents_lock); return -EIO; } - dblock = hfsplus_ext_find_block(hip->cached_extents, - ablock - hip->cached_start); + *max_blocks = hfsplus_ext_find_block(hip->cached_extents, + ablock - hip->cached_start, + dblock); mutex_unlock(&hip->extents_lock); -done: + if (was_dirty) + mark_inode_dirty(inode); + + return 0; +} + +/* Get a block at iblock for inode, possibly allocating if create */ +int hfsplus_get_block(struct inode *inode, sector_t iblock, + struct buffer_head *bh_result, int create) +{ + struct super_block *sb = inode->i_sb; + struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb); + struct hfsplus_inode_info *hip = HFSPLUS_I(inode); + u32 ablock, dblock, mask, max_blocks; + sector_t sector; + int res; + + /* Convert inode block to disk allocation block */ + ablock = iblock >> sbi->fs_shift; + + if (iblock >= hip->fs_blocks) { + if (!create) + return 0; + if (iblock > hip->fs_blocks) + return -EIO; + } else + create = 0; + + res = hfsplus_map_extent(inode, ablock, create, &dblock, &max_blocks, + NULL); + if (res) + return res; + hfs_dbg("ino %llu, iblock %llu - dblock %u\n", inode->i_ino, (long long)iblock, dblock); @@ -292,9 +345,8 @@ int hfsplus_get_block(struct inode *inode, sector_t iblock, hip->phys_size += sb->s_blocksize; hip->fs_blocks++; inode_add_bytes(inode, sb->s_blocksize); - } - if (create || was_dirty) mark_inode_dirty(inode); + } return 0; } diff --git a/fs/hfsplus/hfsplus_fs.h b/fs/hfsplus/hfsplus_fs.h index 1e5b58e6a13f..67586382269b 100644 --- a/fs/hfsplus/hfsplus_fs.h +++ b/fs/hfsplus/hfsplus_fs.h @@ -436,6 +436,8 @@ int hfsplus_ext_cmp_key(const hfsplus_btree_key *k1, int hfsplus_ext_write_extent(struct inode *inode); int hfsplus_get_block(struct inode *inode, sector_t iblock, struct buffer_head *bh_result, int create); +int hfsplus_map_extent(struct inode *inode, u32 ablock, int create, + u32 *dblock, u32 *max_blocks, bool *balloc); int hfsplus_free_fork(struct super_block *sb, u32 cnid, struct hfsplus_fork_raw *fork, int type); int hfsplus_file_extend(struct inode *inode, bool zeroout); -- 2.43.0