From 30ca22c70e3ef0a96ff84de69cd7e8561b416cb2 Mon Sep 17 00:00:00 2001 From: "Patrick J. LoPresti" Date: Thu, 22 Jul 2010 15:03:41 -0700 Subject: [PATCH] ext3/ext4: Factor out disk addressability check As part of adding support for OCFS2 to mount huge volumes, we need to check that the sector_t and page cache of the system are capable of addressing the entire volume. An identical check already appears in ext3 and ext4. This patch moves the addressability check into its own function in fs/libfs.c and modifies ext3 and ext4 to invoke it. [Edited to -EINVAL instead of BUG_ON() for bad blocksize_bits -- Joel] Signed-off-by: Patrick LoPresti Cc: linux-ext4@vger.kernel.org Acked-by: Andreas Dilger Signed-off-by: Joel Becker --- fs/ext3/super.c | 4 ++-- fs/ext4/super.c | 8 +++----- fs/libfs.c | 29 +++++++++++++++++++++++++++++ include/linux/fs.h | 2 ++ 4 files changed, 36 insertions(+), 7 deletions(-) diff --git a/fs/ext3/super.c b/fs/ext3/super.c index 5dbf4dba03c4..a367dd044280 100644 --- a/fs/ext3/super.c +++ b/fs/ext3/super.c @@ -1849,8 +1849,8 @@ static int ext3_fill_super (struct super_block *sb, void *data, int silent) goto failed_mount; } - if (le32_to_cpu(es->s_blocks_count) > - (sector_t)(~0ULL) >> (sb->s_blocksize_bits - 9)) { + if (generic_check_addressable(sb->s_blocksize_bits, + le32_to_cpu(es->s_blocks_count))) { ext3_msg(sb, KERN_ERR, "error: filesystem is too large to mount safely"); if (sizeof(sector_t) < 8) diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 26147746c272..7f47c366bf15 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -2831,15 +2831,13 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) * Test whether we have more sectors than will fit in sector_t, * and whether the max offset is addressable by the page cache. */ - if ((ext4_blocks_count(es) > - (sector_t)(~0ULL) >> (sb->s_blocksize_bits - 9)) || - (ext4_blocks_count(es) > - (pgoff_t)(~0ULL) >> (PAGE_CACHE_SHIFT - sb->s_blocksize_bits))) { + ret = generic_check_addressable(sb->s_blocksize_bits, + ext4_blocks_count(es)); + if (ret) { ext4_msg(sb, KERN_ERR, "filesystem" " too large to mount safely on this system"); if (sizeof(sector_t) < 8) ext4_msg(sb, KERN_WARNING, "CONFIG_LBDAF not enabled"); - ret = -EFBIG; goto failed_mount; } diff --git a/fs/libfs.c b/fs/libfs.c index 0a9da95317f7..8debe7b33769 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -913,6 +913,35 @@ int generic_file_fsync(struct file *file, int datasync) } EXPORT_SYMBOL(generic_file_fsync); +/** + * generic_check_addressable - Check addressability of file system + * @blocksize_bits: log of file system block size + * @num_blocks: number of blocks in file system + * + * Determine whether a file system with @num_blocks blocks (and a + * block size of 2**@blocksize_bits) is addressable by the sector_t + * and page cache of the system. Return 0 if so and -EFBIG otherwise. + */ +int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks) +{ + u64 last_fs_block = num_blocks - 1; + + if (unlikely(num_blocks == 0)) + return 0; + + if ((blocksize_bits < 9) || (blocksize_bits > PAGE_CACHE_SHIFT)) + return -EINVAL; + + if ((last_fs_block > + (sector_t)(~0ULL) >> (blocksize_bits - 9)) || + (last_fs_block > + (pgoff_t)(~0ULL) >> (PAGE_CACHE_SHIFT - blocksize_bits))) { + return -EFBIG; + } + return 0; +} +EXPORT_SYMBOL(generic_check_addressable); + /* * No-op implementation of ->fsync for in-memory filesystems. */ diff --git a/include/linux/fs.h b/include/linux/fs.h index 76041b614758..1a759f40ab9e 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2374,6 +2374,8 @@ extern ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos, extern int generic_file_fsync(struct file *, int); +extern int generic_check_addressable(unsigned, u64); + #ifdef CONFIG_MIGRATION extern int buffer_migrate_page(struct address_space *, struct page *, struct page *); -- 2.20.1