[PATCH] ext4: convert i_fc_lock to spinlock

Harshad Shirwadkar
2024-08-18T04:04:15Z

Convert ext4_inode_info->i_fc_lock to spinlock to avoid sleeping
in invalid contexts.

Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@gmail.com>
---
fs/ext4/ext4.h | 7 +++++--
fs/ext4/fast_commit.c | 24 +++++++++++-------------
fs/ext4/super.c | 2 +-
3 files changed, 17 insertions(+), 16 deletions(-)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 08acd1522..51ae1785a 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1062,8 +1062,11 @@ struct ext4_inode_info {
/* Fast commit wait queue for this inode */
wait_queue_head_t i_fc_wait;

- /* Protect concurrent accesses on i_fc_lblk_start, i_fc_lblk_len */
- struct mutex i_fc_lock;
+ /*
+ * Protect concurrent accesses on i_fc_lblk_start, i_fc_lblk_len
+ * and inode's EXT4_FC_STATE_COMMITTING state bit.
+ */
+ spinlock_t i_fc_lock;

/*
* i_disksize keeps track of what the inode size is ON DISK, not
diff --git a/fs/ext4/fast_commit.c b/fs/ext4/fast_commit.c
index 3926a05ec..8731728cc 100644
--- a/fs/ext4/fast_commit.c
+++ b/fs/ext4/fast_commit.c
@@ -382,7 +382,7 @@ static int ext4_fc_track_template(
int ret;

tid = handle->h_transaction->t_tid;
- mutex_lock(&ei->i_fc_lock);
+ spin_lock(&ei->i_fc_lock);
if (tid == ei->i_sync_tid) {
update = true;
} else {
@@ -390,7 +390,7 @@ static int ext4_fc_track_template(
ei->i_sync_tid = tid;
}
ret = __fc_track_fn(inode, args, update);
- mutex_unlock(&ei->i_fc_lock);
+ spin_unlock(&ei->i_fc_lock);

if (!enqueue)
return ret;
@@ -424,19 +424,19 @@ static int __track_dentry_update(struct inode *inode, void *arg, bool update)
struct super_block *sb = inode->i_sb;
struct ext4_sb_info *sbi = EXT4_SB(sb);

- mutex_unlock(&ei->i_fc_lock);
+ spin_unlock(&ei->i_fc_lock);

if (IS_ENCRYPTED(dir)) {
ext4_fc_mark_ineligible(sb, EXT4_FC_REASON_ENCRYPTED_FILENAME,
NULL);
- mutex_lock(&ei->i_fc_lock);
+ spin_lock(&ei->i_fc_lock);
return -EOPNOTSUPP;
}

node = kmem_cache_alloc(ext4_fc_dentry_cachep, GFP_NOFS);
if (!node) {
ext4_fc_mark_ineligible(sb, EXT4_FC_REASON_NOMEM, NULL);
- mutex_lock(&ei->i_fc_lock);
+ spin_lock(&ei->i_fc_lock);
return -ENOMEM;
}

@@ -448,7 +448,7 @@ static int __track_dentry_update(struct inode *inode, void *arg, bool update)
if (!node->fcd_name.name) {
kmem_cache_free(ext4_fc_dentry_cachep, node);
ext4_fc_mark_ineligible(sb, EXT4_FC_REASON_NOMEM, NULL);
- mutex_lock(&ei->i_fc_lock);
+ spin_lock(&ei->i_fc_lock);
return -ENOMEM;
}
memcpy((u8 *)node->fcd_name.name, dentry->d_name.name,
@@ -482,7 +482,7 @@ static int __track_dentry_update(struct inode *inode, void *arg, bool update)
list_add_tail(&node->fcd_dilist, &ei->i_fc_dilist);
}
spin_unlock(&sbi->s_fc_lock);
- mutex_lock(&ei->i_fc_lock);
+ spin_lock(&ei->i_fc_lock);

return 0;
}
@@ -614,10 +614,8 @@ static int __track_range(struct inode *inode, void *arg, bool update)
struct __track_range_args *__arg =
(struct __track_range_args *)arg;

- if (inode->i_ino < EXT4_FIRST_INO(inode->i_sb)) {
- ext4_debug("Special inode %ld being modified\n", inode->i_ino);
+ if (inode->i_ino < EXT4_FIRST_INO(inode->i_sb))
return -ECANCELED;
- }

oldstart = ei->i_fc_lblk_start;

@@ -902,15 +900,15 @@ static int ext4_fc_write_inode_data(struct inode *inode, u32 *crc)
struct ext4_extent *ex;
int ret;

- mutex_lock(&ei->i_fc_lock);
+ spin_lock(&ei->i_fc_lock);
if (ei->i_fc_lblk_len == 0) {
- mutex_unlock(&ei->i_fc_lock);
+ spin_unlock(&ei->i_fc_lock);
return 0;
}
old_blk_size = ei->i_fc_lblk_start;
new_blk_size = ei->i_fc_lblk_start + ei->i_fc_lblk_len - 1;
ei->i_fc_lblk_len = 0;
- mutex_unlock(&ei->i_fc_lock);
+ spin_unlock(&ei->i_fc_lock);

cur_lblk_off = old_blk_size;
ext4_debug("will try writing %d to %d for inode %ld\n",
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index e72145c4a..d37944839 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1423,7 +1423,7 @@ static struct inode *ext4_alloc_inode(struct super_block *sb)
atomic_set(&ei->i_unwritten, 0);
INIT_WORK(&ei->i_rsv_conversion_work, ext4_end_io_rsv_work);
ext4_fc_init_inode(&ei->vfs_inode);
- mutex_init(&ei->i_fc_lock);
+ spin_lock_init(&ei->i_fc_lock);
return &ei->vfs_inode;
}

--
2.46.0.184.g6999bdac58-goog