ext4: minor defrag code improvements

Modify the error returns for two file types that can't be defragged to
more clearly communicate those restrictions to a caller.  When the
defrag code is applied to swap files, return -ETXTBSY, and when applied
to quota files, return -EOPNOTSUPP.  Move an extent tree search whose
results are only occasionally required to the site always requiring them
for improved efficiency.  Address a few typos.

Signed-off-by: Eric Whitney <enwlinux@gmail.com>
Link: https://lore.kernel.org/r/20220722163910.268564-1-enwlinux@gmail.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c
index 701f1d6..2b83621 100644 (file)
--- a/fs/ext4/move_extent.c
+++ b/fs/ext4/move_extent.c
@@ -472,19 +472,17 @@ mext_check_arguments(struct inode *orig_inode,
        if (IS_IMMUTABLE(donor_inode) || IS_APPEND(donor_inode))
                return -EPERM;
 
-       /* Ext4 move extent does not support swapfile */
+       /* Ext4 move extent does not support swap files */
        if (IS_SWAPFILE(orig_inode) || IS_SWAPFILE(donor_inode)) {
-               ext4_debug("ext4 move extent: The argument files should "
-                       "not be swapfile [ino:orig %lu, donor %lu]\n",
+               ext4_debug("ext4 move extent: The argument files should not be swap files [ino:orig %lu, donor %lu]\n",
                        orig_inode->i_ino, donor_inode->i_ino);
-               return -EBUSY;
+               return -ETXTBSY;
        }
 
        if (ext4_is_quota_file(orig_inode) && ext4_is_quota_file(donor_inode)) {
-               ext4_debug("ext4 move extent: The argument files should "
-                       "not be quota files [ino:orig %lu, donor %lu]\n",
+               ext4_debug("ext4 move extent: The argument files should not be quota files [ino:orig %lu, donor %lu]\n",
                        orig_inode->i_ino, donor_inode->i_ino);
-               return -EBUSY;
+               return -EOPNOTSUPP;
        }
 
        /* Ext4 move extent supports only extent based file */
@@ -631,11 +629,11 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp, __u64 orig_blk,
                if (ret)
                        goto out;
                ex = path[path->p_depth].p_ext;
-               next_blk = ext4_ext_next_allocated_block(path);
                cur_blk = le32_to_cpu(ex->ee_block);
                cur_len = ext4_ext_get_actual_len(ex);
                /* Check hole before the start pos */
                if (cur_blk + cur_len - 1 < o_start) {
+                       next_blk = ext4_ext_next_allocated_block(path);
                        if (next_blk == EXT_MAX_BLOCKS) {
                                ret = -ENODATA;
                                goto out;
@@ -663,7 +661,7 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp, __u64 orig_blk,
                donor_page_index = d_start >> (PAGE_SHIFT -
                                               donor_inode->i_blkbits);
                offset_in_page = o_start % blocks_per_page;
-               if (cur_len > blocks_per_page- offset_in_page)
+               if (cur_len > blocks_per_page - offset_in_page)
                        cur_len = blocks_per_page - offset_in_page;
                /*
                 * Up semaphore to avoid following problems: