diff options
Diffstat (limited to 'fs/erofs/utils.c')
| -rw-r--r-- | fs/erofs/utils.c | 90 |
1 files changed, 33 insertions, 57 deletions
diff --git a/fs/erofs/utils.c b/fs/erofs/utils.c index fddc5059c930..52d0be10f1aa 100644 --- a/fs/erofs/utils.c +++ b/fs/erofs/utils.c @@ -37,9 +37,6 @@ void *erofs_get_pcpubuf(unsigned int pagenr) /* global shrink count (for all mounted EROFS instances) */ static atomic_long_t erofs_global_shrink_cnt; -#define __erofs_workgroup_get(grp) atomic_inc(&(grp)->refcount) -#define __erofs_workgroup_put(grp) atomic_dec(&(grp)->refcount) - static int erofs_workgroup_get(struct erofs_workgroup *grp) { int o; @@ -66,7 +63,7 @@ struct erofs_workgroup *erofs_find_workgroup(struct super_block *sb, repeat: rcu_read_lock(); - grp = radix_tree_lookup(&sbi->workstn_tree, index); + grp = xa_load(&sbi->managed_pslots, index); if (grp) { if (erofs_workgroup_get(grp)) { /* prefer to relax rcu read side */ @@ -80,43 +77,37 @@ repeat: return grp; } -int erofs_register_workgroup(struct super_block *sb, - struct erofs_workgroup *grp) +struct erofs_workgroup *erofs_insert_workgroup(struct super_block *sb, + struct erofs_workgroup *grp) { - struct erofs_sb_info *sbi; - int err; - - /* grp shouldn't be broken or used before */ - if (atomic_read(&grp->refcount) != 1) { - DBG_BUGON(1); - return -EINVAL; - } - - err = radix_tree_preload(GFP_NOFS); - if (err) - return err; - - sbi = EROFS_SB(sb); - xa_lock(&sbi->workstn_tree); + struct erofs_sb_info *const sbi = EROFS_SB(sb); + struct erofs_workgroup *pre; /* - * Bump up reference count before making this workgroup - * visible to other users in order to avoid potential UAF - * without serialized by workstn_lock. + * Bump up a reference count before making this visible + * to others for the XArray in order to avoid potential + * UAF without serialized by xa_lock. */ - __erofs_workgroup_get(grp); - - err = radix_tree_insert(&sbi->workstn_tree, grp->index, grp); - if (err) - /* - * it's safe to decrease since the workgroup isn't visible - * and refcount >= 2 (cannot be freezed). - */ - __erofs_workgroup_put(grp); + atomic_inc(&grp->refcount); - xa_unlock(&sbi->workstn_tree); - radix_tree_preload_end(); - return err; +repeat: + xa_lock(&sbi->managed_pslots); + pre = __xa_cmpxchg(&sbi->managed_pslots, grp->index, + NULL, grp, GFP_NOFS); + 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; + } + atomic_dec(&grp->refcount); + grp = pre; + } + xa_unlock(&sbi->managed_pslots); + return grp; } static void __erofs_workgroup_free(struct erofs_workgroup *grp) @@ -155,7 +146,7 @@ static bool erofs_try_to_release_workgroup(struct erofs_sb_info *sbi, /* * Note that all cached pages should be unattached - * before deleted from the radix tree. Otherwise some + * before deleted from the XArray. Otherwise some * cached pages could be still attached to the orphan * old workgroup when the new one is available in the tree. */ @@ -169,7 +160,7 @@ static bool erofs_try_to_release_workgroup(struct erofs_sb_info *sbi, * however in order to avoid some race conditions, add a * DBG_BUGON to observe this in advance. */ - DBG_BUGON(radix_tree_delete(&sbi->workstn_tree, grp->index) != grp); + DBG_BUGON(xa_erase(&sbi->managed_pslots, grp->index) != grp); /* * If managed cache is on, last refcount should indicate @@ -182,22 +173,11 @@ static bool erofs_try_to_release_workgroup(struct erofs_sb_info *sbi, static unsigned long erofs_shrink_workstation(struct erofs_sb_info *sbi, unsigned long nr_shrink) { - pgoff_t first_index = 0; - void *batch[PAGEVEC_SIZE]; + struct erofs_workgroup *grp; unsigned int freed = 0; + unsigned long index; - int i, found; -repeat: - xa_lock(&sbi->workstn_tree); - - found = radix_tree_gang_lookup(&sbi->workstn_tree, - batch, first_index, PAGEVEC_SIZE); - - for (i = 0; i < found; ++i) { - struct erofs_workgroup *grp = batch[i]; - - first_index = grp->index + 1; - + xa_for_each(&sbi->managed_pslots, index, grp) { /* try to shrink each valid workgroup */ if (!erofs_try_to_release_workgroup(sbi, grp)) continue; @@ -206,10 +186,6 @@ repeat: if (!--nr_shrink) break; } - xa_unlock(&sbi->workstn_tree); - - if (i && nr_shrink) - goto repeat; return freed; } @@ -286,7 +262,7 @@ static unsigned long erofs_shrink_scan(struct shrinker *shrink, spin_unlock(&erofs_sb_list_lock); sbi->shrinker_run_no = run_no; - freed += erofs_shrink_workstation(sbi, nr); + freed += erofs_shrink_workstation(sbi, nr - freed); spin_lock(&erofs_sb_list_lock); /* Get the next list element before we move this one */ |