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Message-ID: <36d1653d-249a-47b0-a87c-1216ed5bf1ca@kernel.org>
Date: Thu, 7 Nov 2024 11:09:46 +0800
From: Chao Yu <chao@...nel.org>
To: Gao Xiang <hsiangkao@...ux.alibaba.com>, linux-erofs@...ts.ozlabs.org
Cc: Chao Yu <chao@...nel.org>, Chunhai Guo <guochunhai@...o.com>,
LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/3] erofs: get rid of erofs_{find,insert}_workgroup
On 2024/10/21 11:53, Gao Xiang wrote:
> Just fold them into the only two callers since
> they are simple enough.
>
> Signed-off-by: Gao Xiang <hsiangkao@...ux.alibaba.com>
> ---
> v1: https://lore.kernel.org/r/20241017115705.877515-1-hsiangkao@linux.alibaba.com
> change since v1:
> - !grp case should be handled properly mentioned by Chunhai;
>
> fs/erofs/internal.h | 5 +----
> fs/erofs/zdata.c | 38 +++++++++++++++++++++++++---------
> fs/erofs/zutil.c | 50 +--------------------------------------------
> 3 files changed, 30 insertions(+), 63 deletions(-)
>
> diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
> index 4efd578d7c62..8081ee43cd83 100644
> --- a/fs/erofs/internal.h
> +++ b/fs/erofs/internal.h
> @@ -457,10 +457,7 @@ void erofs_release_pages(struct page **pagepool);
>
> #ifdef CONFIG_EROFS_FS_ZIP
> void erofs_workgroup_put(struct erofs_workgroup *grp);
> -struct erofs_workgroup *erofs_find_workgroup(struct super_block *sb,
> - pgoff_t index);
> -struct erofs_workgroup *erofs_insert_workgroup(struct super_block *sb,
> - struct erofs_workgroup *grp);
> +bool erofs_workgroup_get(struct erofs_workgroup *grp);
> void erofs_workgroup_free_rcu(struct erofs_workgroup *grp);
> void erofs_shrinker_register(struct super_block *sb);
> void erofs_shrinker_unregister(struct super_block *sb);
> diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
> index a569ff9dfd04..bb1b73d99d07 100644
> --- a/fs/erofs/zdata.c
> +++ b/fs/erofs/zdata.c
> @@ -714,9 +714,10 @@ static int z_erofs_register_pcluster(struct z_erofs_decompress_frontend *fe)
> {
> struct erofs_map_blocks *map = &fe->map;
> struct super_block *sb = fe->inode->i_sb;
> + struct erofs_sb_info *sbi = EROFS_SB(sb);
> bool ztailpacking = map->m_flags & EROFS_MAP_META;
> struct z_erofs_pcluster *pcl;
> - struct erofs_workgroup *grp;
> + struct erofs_workgroup *grp, *pre;
> int err;
>
> if (!(map->m_flags & EROFS_MAP_ENCODED) ||
> @@ -752,15 +753,23 @@ static int z_erofs_register_pcluster(struct z_erofs_decompress_frontend *fe)
> pcl->obj.index = 0; /* which indicates ztailpacking */
> } else {
> pcl->obj.index = erofs_blknr(sb, map->m_pa);
> -
> - grp = erofs_insert_workgroup(fe->inode->i_sb, &pcl->obj);
> - if (IS_ERR(grp)) {
> - err = PTR_ERR(grp);
> - goto err_out;
> + while (1) {
> + xa_lock(&sbi->managed_pslots);
> + pre = __xa_cmpxchg(&sbi->managed_pslots, grp->index,
> + NULL, grp, GFP_KERNEL);
> + if (!pre || xa_is_err(pre) || erofs_workgroup_get(pre)) {
> + xa_unlock(&sbi->managed_pslots);
> + break;
> + }
> + /* try to legitimize the current in-tree one */
> + xa_unlock(&sbi->managed_pslots);
> + cond_resched();
> }
> -
> - if (grp != &pcl->obj) {
Do we need to keep this logic?
Thanks,
> - fe->pcl = container_of(grp,
> + if (xa_is_err(pre)) {
> + err = xa_err(pre);
> + goto err_out;
> + } else if (pre) {
> + fe->pcl = container_of(pre,
> struct z_erofs_pcluster, obj);
> err = -EEXIST;
> goto err_out;
> @@ -789,7 +798,16 @@ static int z_erofs_pcluster_begin(struct z_erofs_decompress_frontend *fe)
> DBG_BUGON(fe->owned_head == Z_EROFS_PCLUSTER_NIL);
>
> if (!(map->m_flags & EROFS_MAP_META)) {
> - grp = erofs_find_workgroup(sb, blknr);
> + while (1) {
> + rcu_read_lock();
> + grp = xa_load(&EROFS_SB(sb)->managed_pslots, blknr);
> + if (!grp || erofs_workgroup_get(grp)) {
> + DBG_BUGON(grp && blknr != grp->index);
> + rcu_read_unlock();
> + break;
> + }
> + rcu_read_unlock();
> + }
> } else if ((map->m_pa & ~PAGE_MASK) + map->m_plen > PAGE_SIZE) {
> DBG_BUGON(1);
> return -EFSCORRUPTED;
> diff --git a/fs/erofs/zutil.c b/fs/erofs/zutil.c
> index 37afe2024840..218b0249a482 100644
> --- a/fs/erofs/zutil.c
> +++ b/fs/erofs/zutil.c
> @@ -214,7 +214,7 @@ void erofs_release_pages(struct page **pagepool)
> }
> }
>
> -static bool erofs_workgroup_get(struct erofs_workgroup *grp)
> +bool erofs_workgroup_get(struct erofs_workgroup *grp)
> {
> if (lockref_get_not_zero(&grp->lockref))
> return true;
> @@ -231,54 +231,6 @@ static bool erofs_workgroup_get(struct erofs_workgroup *grp)
> return true;
> }
>
> -struct erofs_workgroup *erofs_find_workgroup(struct super_block *sb,
> - pgoff_t index)
> -{
> - struct erofs_sb_info *sbi = EROFS_SB(sb);
> - struct erofs_workgroup *grp;
> -
> -repeat:
> - rcu_read_lock();
> - grp = xa_load(&sbi->managed_pslots, index);
> - if (grp) {
> - if (!erofs_workgroup_get(grp)) {
> - /* prefer to relax rcu read side */
> - rcu_read_unlock();
> - goto repeat;
> - }
> -
> - DBG_BUGON(index != grp->index);
> - }
> - rcu_read_unlock();
> - return grp;
> -}
> -
> -struct erofs_workgroup *erofs_insert_workgroup(struct super_block *sb,
> - struct erofs_workgroup *grp)
> -{
> - struct erofs_sb_info *const sbi = EROFS_SB(sb);
> - struct erofs_workgroup *pre;
> -
> - DBG_BUGON(grp->lockref.count < 1);
> -repeat:
> - xa_lock(&sbi->managed_pslots);
> - pre = __xa_cmpxchg(&sbi->managed_pslots, grp->index,
> - NULL, grp, GFP_KERNEL);
> - if (pre) {
> - if (xa_is_err(pre)) {
> - pre = ERR_PTR(xa_err(pre));
> - } else if (!erofs_workgroup_get(pre)) {
> - /* try to legitimize the current in-tree one */
> - xa_unlock(&sbi->managed_pslots);
> - cond_resched();
> - goto repeat;
> - }
> - grp = pre;
> - }
> - xa_unlock(&sbi->managed_pslots);
> - return grp;
> -}
> -
> static void __erofs_workgroup_free(struct erofs_workgroup *grp)
> {
> atomic_long_dec(&erofs_global_shrink_cnt);
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