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Message-ID: <20240621161934.6u36oo3yhofuhlnk@quack3>
Date: Fri, 21 Jun 2024 18:19:34 +0200
From: Jan Kara <jack@...e.cz>
To: Harshad Shirwadkar <harshadshirwadkar@...il.com>
Cc: linux-ext4@...r.kernel.org, tytso@....edu, saukad@...gle.com,
harshads@...gle.com
Subject: Re: [PATCH v6 01/10] ext4: convert i_fc_lock to spinlock
On Wed 29-05-24 01:19:54, Harshad Shirwadkar wrote:
> Convert ext4_inode_info->i_fc_lock to spinlock to avoid sleeping
> in invalid contexts.
>
> Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@...il.com>
Looks good. Feel free to add:
Reviewed-by: Jan Kara <jack@...e.cz>
Honza
> ---
> 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 983dad8c07ec..611b8c80d99c 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 87c009e0c59a..a1aadebfcd66 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;
>
> @@ -896,15 +894,15 @@ 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 f9a4a4e89dac..77173ec91e49 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -1436,7 +1436,7 @@ 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;
> }
>
> --
> 2.45.1.288.g0e0cd299f1-goog
>
>
--
Jan Kara <jack@...e.com>
SUSE Labs, CR
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