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Commit ec7268ce authored by Eric Sandeen's avatar Eric Sandeen Committed by Al Viro
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ext4: use core vfs llseek code for dir seeks 



Use the new functionality in generic_file_llseek_size() to
accept a custom EOF position, and un-cut-and-paste all the
vfs llseek code from ext4.

Also fix up comments on ext4_llseek() to reflect reality.

Signed-off-by: default avatarEric Sandeen <sandeen@redaht.com>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent e8b96eb5

fs/ext4/dir.c

+14 −61
Original line number Diff line number Diff line
@@ -324,74 +324,27 @@ static inline loff_t ext4_get_htree_eof(struct file *filp) 




/*

 * ext4_dir_llseek() based on generic_file_llseek() to handle both

 * non-htree and htree directories, where the "offset" is in terms

 * of the filename hash value instead of the byte offset.

 * ext4_dir_llseek() calls generic_file_llseek_size to handle htree

 * directories, where the "offset" is in terms of the filename hash

 * value instead of the byte offset.

 *

 * NOTE: offsets obtained *before* ext4_set_inode_flag(dir, EXT4_INODE_INDEX)

 *       will be invalid once the directory was converted into a dx directory

 * Because we may return a 64-bit hash that is well beyond offset limits,

 * we need to pass the max hash as the maximum allowable offset in

 * the htree directory case.

 *

 * For non-htree, ext4_llseek already chooses the proper max offset.

 */

loff_t ext4_dir_llseek(struct file *file, loff_t offset, int origin)

{

	struct inode *inode = file->f_mapping->host;

	loff_t ret = -EINVAL;

	int dx_dir = is_dx_dir(inode);

	loff_t htree_max = ext4_get_htree_eof(file);



	mutex_lock(&inode->i_mutex);



	/* NOTE: relative offsets with dx directories might not work

	 *       as expected, as it is difficult to figure out the

	 *       correct offset between dx hashes */



	switch (origin) {

	case SEEK_END:

		if (unlikely(offset > 0))

			goto out_err; /* not supported for directories */



		/* so only negative offsets are left, does that have a

		 * meaning for directories at all? */

		if (dx_dir)

			offset += ext4_get_htree_eof(file);

	if (likely(dx_dir))

		return generic_file_llseek_size(file, offset, origin,

						    htree_max, htree_max);

	else

			offset += inode->i_size;

		break;

	case SEEK_CUR:

		/*

		 * Here we special-case the lseek(fd, 0, SEEK_CUR)

		 * position-querying operation.  Avoid rewriting the "same"

		 * f_pos value back to the file because a concurrent read(),

		 * write() or lseek() might have altered it

		 */

		if (offset == 0) {

			offset = file->f_pos;

			goto out_ok;

		}



		offset += file->f_pos;

		break;

	}



	if (unlikely(offset < 0))

		goto out_err;



	if (!dx_dir) {

		if (offset > inode->i_sb->s_maxbytes)

			goto out_err;

	} else if (offset > ext4_get_htree_eof(file))

		goto out_err;



	/* Special lock needed here? */

	if (offset != file->f_pos) {

		file->f_pos = offset;

		file->f_version = 0;

	}



out_ok:

	ret = offset;

out_err:

	mutex_unlock(&inode->i_mutex);



	return ret;

		return ext4_llseek(file, offset, origin);

}



/*

fs/ext4/file.c

+3 −3
Original line number Diff line number Diff line
@@ -211,9 +211,9 @@ static int ext4_file_open(struct inode * inode, struct file * filp) 
}



/*

 * ext4_llseek() copied from generic_file_llseek() to handle both

 * block-mapped and extent-mapped maxbytes values. This should

 * otherwise be identical with generic_file_llseek().

 * ext4_llseek() handles both block-mapped and extent-mapped maxbytes values

 * by calling generic_file_llseek_size() with the appropriate maxbytes

 * value for each.

 */

loff_t ext4_llseek(struct file *file, loff_t offset, int origin)

{