diff options
| -rw-r--r-- | fs/ext4/file.c | 97 |
1 files changed, 50 insertions, 47 deletions
diff --git a/fs/ext4/file.c b/fs/ext4/file.c index 2a822d30e73f..9facb4dc5c70 100644 --- a/fs/ext4/file.c +++ b/fs/ext4/file.c @@ -88,6 +88,51 @@ ext4_unaligned_aio(struct inode *inode, struct iov_iter *from, loff_t pos) return 0; } +/* Is IO overwriting allocated and initialized blocks? */ +static bool ext4_overwrite_io(struct inode *inode, loff_t pos, loff_t len) +{ + struct ext4_map_blocks map; + unsigned int blkbits = inode->i_blkbits; + int err, blklen; + + if (pos + len > i_size_read(inode)) + return false; + + map.m_lblk = pos >> blkbits; + map.m_len = EXT4_MAX_BLOCKS(len, pos, blkbits); + blklen = map.m_len; + + err = ext4_map_blocks(NULL, inode, &map, 0); + /* + * 'err==len' means that all of the blocks have been preallocated, + * regardless of whether they have been initialized or not. To exclude + * unwritten extents, we need to check m_flags. + */ + return err == blklen && (map.m_flags & EXT4_MAP_MAPPED); +} + +static ssize_t ext4_write_checks(struct kiocb *iocb, struct iov_iter *from) +{ + struct inode *inode = file_inode(iocb->ki_filp); + ssize_t ret; + + ret = generic_write_checks(iocb, from); + if (ret <= 0) + return ret; + /* + * If we have encountered a bitmap-format file, the size limit + * is smaller than s_maxbytes, which is for extent-mapped files. + */ + if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) { + struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb); + + if (iocb->ki_pos >= sbi->s_bitmap_maxbytes) + return -EFBIG; + iov_iter_truncate(from, sbi->s_bitmap_maxbytes - iocb->ki_pos); + } + return iov_iter_count(from); +} + static ssize_t ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from) { @@ -98,7 +143,7 @@ ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from) ssize_t ret; inode_lock(inode); - ret = generic_write_checks(iocb, from); + ret = ext4_write_checks(iocb, from); if (ret <= 0) goto out; @@ -114,53 +159,11 @@ ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from) ext4_unwritten_wait(inode); } - /* - * If we have encountered a bitmap-format file, the size limit - * is smaller than s_maxbytes, which is for extent-mapped files. - */ - if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) { - struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb); - - if (iocb->ki_pos >= sbi->s_bitmap_maxbytes) { - ret = -EFBIG; - goto out; - } - iov_iter_truncate(from, sbi->s_bitmap_maxbytes - iocb->ki_pos); - } - iocb->private = &overwrite; - if (o_direct) { - size_t length = iov_iter_count(from); - loff_t pos = iocb->ki_pos; - - /* check whether we do a DIO overwrite or not */ - if (ext4_should_dioread_nolock(inode) && !unaligned_aio && - pos + length <= i_size_read(inode)) { - struct ext4_map_blocks map; - unsigned int blkbits = inode->i_blkbits; - int err, len; - - map.m_lblk = pos >> blkbits; - map.m_len = EXT4_MAX_BLOCKS(length, pos, blkbits); - len = map.m_len; - - err = ext4_map_blocks(NULL, inode, &map, 0); - /* - * 'err==len' means that all of blocks has - * been preallocated no matter they are - * initialized or not. For excluding - * unwritten extents, we need to check - * m_flags. There are two conditions that - * indicate for initialized extents. 1) If we - * hit extent cache, EXT4_MAP_MAPPED flag is - * returned; 2) If we do a real lookup, - * non-flags are returned. So we should check - * these two conditions. - */ - if (err == len && (map.m_flags & EXT4_MAP_MAPPED)) - overwrite = 1; - } - } + /* Check whether we do a DIO overwrite or not */ + if (o_direct && ext4_should_dioread_nolock(inode) && !unaligned_aio && + ext4_overwrite_io(inode, iocb->ki_pos, iov_iter_count(from))) + overwrite = 1; ret = __generic_file_write_iter(iocb, from); inode_unlock(inode); |