Factor out checks of 'from' and whether we are overwriting out of
ext4_file_write_iter() so that the function is easier to follow.
Signed-off-by: Jan Kara <jack@xxxxxxx>
---
fs/ext4/file.c | 97 ++++++++++++++++++++++++++++++----------------------------
1 file 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);
--
2.6.6
--
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