This is a note to let you know that I've just added the patch titled
ext4: add a new helper to check if es must be kept
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ext4-add-a-new-helper-to-check-if-es-must-be-kept.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 6e202c205084fb4929289156017cc286a62d9782
Author: Baokun Li <libaokun1@xxxxxxxxxx>
Date: Mon Apr 24 11:38:36 2023 +0800
ext4: add a new helper to check if es must be kept
[ Upstream commit 9649eb18c6288f514cacffdd699d5cd999c2f8f6 ]
In the extent status tree, we have extents which we can just drop without
issues and extents we must not drop - this depends on the extent's status
- currently ext4_es_is_delayed() extents must stay, others may be dropped.
A helper function is added to help determine if the current extent can
be dropped, although only ext4_es_is_delayed() extents cannot be dropped
currently.
Suggested-by: Jan Kara <jack@xxxxxxx>
Signed-off-by: Baokun Li <libaokun1@xxxxxxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
Link: https://lore.kernel.org/r/20230424033846.4732-3-libaokun1@xxxxxxxxxx
Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
Stable-dep-of: 8e387c89e96b ("ext4: make sure allocate pending entry not fail")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/ext4/extents_status.c b/fs/ext4/extents_status.c
index cfd05e016f181..59812c5bbe1ba 100644
--- a/fs/ext4/extents_status.c
+++ b/fs/ext4/extents_status.c
@@ -439,6 +439,19 @@ static void ext4_es_list_del(struct inode *inode)
spin_unlock(&sbi->s_es_lock);
}
+/*
+ * Returns true if we cannot fail to allocate memory for this extent_status
+ * entry and cannot reclaim it until its status changes.
+ */
+static inline bool ext4_es_must_keep(struct extent_status *es)
+{
+ /* fiemap, bigalloc, and seek_data/hole need to use it. */
+ if (ext4_es_is_delayed(es))
+ return true;
+
+ return false;
+}
+
static struct extent_status *
ext4_es_alloc_extent(struct inode *inode, ext4_lblk_t lblk, ext4_lblk_t len,
ext4_fsblk_t pblk)
@@ -451,10 +464,8 @@ ext4_es_alloc_extent(struct inode *inode, ext4_lblk_t lblk, ext4_lblk_t len,
es->es_len = len;
es->es_pblk = pblk;
- /*
- * We don't count delayed extent because we never try to reclaim them
- */
- if (!ext4_es_is_delayed(es)) {
+ /* We never try to reclaim a must kept extent, so we don't count it. */
+ if (!ext4_es_must_keep(es)) {
if (!EXT4_I(inode)->i_es_shk_nr++)
ext4_es_list_add(inode);
percpu_counter_inc(&EXT4_SB(inode->i_sb)->
@@ -472,8 +483,8 @@ static void ext4_es_free_extent(struct inode *inode, struct extent_status *es)
EXT4_I(inode)->i_es_all_nr--;
percpu_counter_dec(&EXT4_SB(inode->i_sb)->s_es_stats.es_stats_all_cnt);
- /* Decrease the shrink counter when this es is not delayed */
- if (!ext4_es_is_delayed(es)) {
+ /* Decrease the shrink counter when we can reclaim the extent. */
+ if (!ext4_es_must_keep(es)) {
BUG_ON(EXT4_I(inode)->i_es_shk_nr == 0);
if (!--EXT4_I(inode)->i_es_shk_nr)
ext4_es_list_del(inode);
@@ -842,7 +853,7 @@ int ext4_es_insert_extent(struct inode *inode, ext4_lblk_t lblk,
if (err == -ENOMEM && __es_shrink(EXT4_SB(inode->i_sb),
128, EXT4_I(inode)))
goto retry;
- if (err == -ENOMEM && !ext4_es_is_delayed(&newes))
+ if (err == -ENOMEM && !ext4_es_must_keep(&newes))
err = 0;
if (sbi->s_cluster_ratio > 1 && test_opt(inode->i_sb, DELALLOC) &&
@@ -1683,11 +1694,8 @@ static int es_do_reclaim_extents(struct ext4_inode_info *ei, ext4_lblk_t end,
(*nr_to_scan)--;
node = rb_next(&es->rb_node);
- /*
- * We can't reclaim delayed extent from status tree because
- * fiemap, bigallic, and seek_data/hole need to use it.
- */
- if (ext4_es_is_delayed(es))
+
+ if (ext4_es_must_keep(es))
goto next;
if (ext4_es_is_referenced(es)) {
ext4_es_clear_referenced(es);
@@ -1751,7 +1759,7 @@ void ext4_clear_inode_es(struct inode *inode)
while (node) {
es = rb_entry(node, struct extent_status, rb_node);
node = rb_next(node);
- if (!ext4_es_is_delayed(es)) {
+ if (!ext4_es_must_keep(es)) {
rb_erase(&es->rb_node, &tree->root);
ext4_es_free_extent(inode, es);
}
