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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: Eric Sandeen <sandeen@redaht.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Eric Sandeen 2012-04-30 13:14:03 -05:00 committed by Al Viro
parent e8b96eb503
commit ec7268ce21
2 changed files with 17 additions and 64 deletions
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75
fs/ext4/dir.c
View File

@ -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);
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;
if (likely(dx_dir))
return generic_file_llseek_size(file, offset, origin,
htree_max, htree_max);
else
return ext4_llseek(file, offset, origin);
}
/*

6
fs/ext4/file.c
View File

@ -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)
{