ext4: using nofail preallocation in ext4_es_insert_extent()

Similar to in ext4_es_insert_delayed_block(), we use preallocations that
do not fail to avoid inconsistencies, but we do not care about es that are
not must be kept, and we return 0 even if such es memory allocation fails.

Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230424033846.4732-9-libaokun1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/ext4/extents_status.c b/fs/ext4/extents_status.c
index 1890df2..807ccc3 100644 (file)
--- a/fs/ext4/extents_status.c
+++ b/fs/ext4/extents_status.c
@@ -838,8 +838,11 @@ int ext4_es_insert_extent(struct inode *inode, ext4_lblk_t lblk,
 {
        struct extent_status newes;
        ext4_lblk_t end = lblk + len - 1;
-       int err = 0;
+       int err1 = 0;
+       int err2 = 0;
        struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+       struct extent_status *es1 = NULL;
+       struct extent_status *es2 = NULL;
 
        if (EXT4_SB(inode->i_sb)->s_mount_state & EXT4_FC_REPLAY)
                return 0;
@@ -867,29 +870,40 @@ int ext4_es_insert_extent(struct inode *inode, ext4_lblk_t lblk,
 
        ext4_es_insert_extent_check(inode, &newes);
 
+retry:
+       if (err1 && !es1)
+               es1 = __es_alloc_extent(true);
+       if ((err1 || err2) && !es2)
+               es2 = __es_alloc_extent(true);
        write_lock(&EXT4_I(inode)->i_es_lock);
-       err = __es_remove_extent(inode, lblk, end, NULL, NULL);
-       if (err != 0)
+
+       err1 = __es_remove_extent(inode, lblk, end, NULL, es1);
+       if (err1 != 0)
+               goto error;
+
+       err2 = __es_insert_extent(inode, &newes, es2);
+       if (err2 == -ENOMEM && !ext4_es_must_keep(&newes))
+               err2 = 0;
+       if (err2 != 0)
                goto error;
-retry:
-       err = __es_insert_extent(inode, &newes, NULL);
-       if (err == -ENOMEM && __es_shrink(EXT4_SB(inode->i_sb),
-                                         128, EXT4_I(inode)))
-               goto retry;
-       if (err == -ENOMEM && !ext4_es_must_keep(&newes))
-               err = 0;
 
        if (sbi->s_cluster_ratio > 1 && test_opt(inode->i_sb, DELALLOC) &&
            (status & EXTENT_STATUS_WRITTEN ||
             status & EXTENT_STATUS_UNWRITTEN))
                __revise_pending(inode, lblk, len);
 
+       /* es is pre-allocated but not used, free it. */
+       if (es1 && !es1->es_len)
+               __es_free_extent(es1);
+       if (es2 && !es2->es_len)
+               __es_free_extent(es2);
 error:
        write_unlock(&EXT4_I(inode)->i_es_lock);
+       if (err1 || err2)
+               goto retry;
 
        ext4_es_print_tree(inode);
-
-       return err;
+       return 0;
 }
 
 /*