From 524887347fcb67faa0a63dd3c4c02ab48d4968d4 Mon Sep 17 00:00:00 2001 From: Gao Xiang Date: Sat, 10 Apr 2021 03:06:30 +0800 Subject: erofs: introduce multipage per-CPU buffers To deal the with the cases which inplace decompression is infeasible for some inplace I/O. Per-CPU buffers was introduced to get rid of page allocation latency and thrash for low-latency decompression algorithms such as lz4. For the big pcluster feature, introduce multipage per-CPU buffers to keep such inplace I/O pclusters temporarily as well but note that per-CPU pages are just consecutive virtually. When a new big pcluster fs is mounted, its max pclustersize will be read and per-CPU buffers can be growed if needed. Shrinking adjustable per-CPU buffers is more complex (because we don't know if such size is still be used), so currently just release them all when unloading. Link: https://lore.kernel.org/r/20210409190630.19569-1-xiang@kernel.org Acked-by: Chao Yu Signed-off-by: Gao Xiang --- fs/erofs/Makefile | 2 +- fs/erofs/decompressor.c | 8 ++- fs/erofs/internal.h | 25 +++----- fs/erofs/pcpubuf.c | 148 ++++++++++++++++++++++++++++++++++++++++++++++++ fs/erofs/super.c | 2 + fs/erofs/utils.c | 12 ---- 6 files changed, 163 insertions(+), 34 deletions(-) create mode 100644 fs/erofs/pcpubuf.c diff --git a/fs/erofs/Makefile b/fs/erofs/Makefile index af159539fc1b..1f9aced49070 100644 --- a/fs/erofs/Makefile +++ b/fs/erofs/Makefile @@ -1,6 +1,6 @@ # SPDX-License-Identifier: GPL-2.0-only obj-$(CONFIG_EROFS_FS) += erofs.o -erofs-objs := super.o inode.o data.o namei.o dir.o utils.o +erofs-objs := super.o inode.o data.o namei.o dir.o utils.o pcpubuf.o erofs-$(CONFIG_EROFS_FS_XATTR) += xattr.o erofs-$(CONFIG_EROFS_FS_ZIP) += decompressor.o zmap.o zdata.o diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c index 27aa6a99b371..fb4838c0f0df 100644 --- a/fs/erofs/decompressor.c +++ b/fs/erofs/decompressor.c @@ -47,7 +47,9 @@ int z_erofs_load_lz4_config(struct super_block *sb, EROFS_SB(sb)->lz4.max_distance_pages = distance ? DIV_ROUND_UP(distance, PAGE_SIZE) + 1 : LZ4_MAX_DISTANCE_PAGES; - return 0; + + /* TODO: use max pclusterblks after bigpcluster is enabled */ + return erofs_pcpubuf_growsize(1); } static int z_erofs_lz4_prepare_destpages(struct z_erofs_decompress_req *rq, @@ -114,7 +116,7 @@ static void *generic_copy_inplace_data(struct z_erofs_decompress_req *rq, * pages should be copied in order to avoid being overlapped. */ struct page **in = rq->in; - u8 *const tmp = erofs_get_pcpubuf(0); + u8 *const tmp = erofs_get_pcpubuf(1); u8 *tmpp = tmp; unsigned int inlen = rq->inputsize - pageofs_in; unsigned int count = min_t(uint, inlen, PAGE_SIZE - pageofs_in); @@ -271,7 +273,7 @@ static int z_erofs_decompress_generic(struct z_erofs_decompress_req *rq, * compressed data is preferred. */ if (rq->outputsize <= PAGE_SIZE * 7 / 8) { - dst = erofs_get_pcpubuf(0); + dst = erofs_get_pcpubuf(1); if (IS_ERR(dst)) return PTR_ERR(dst); diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h index 05b02f99324c..4db085413304 100644 --- a/fs/erofs/internal.h +++ b/fs/erofs/internal.h @@ -197,9 +197,6 @@ static inline int erofs_wait_on_workgroup_freezed(struct erofs_workgroup *grp) /* hard limit of pages per compressed cluster */ #define Z_EROFS_CLUSTER_MAX_PAGES (CONFIG_EROFS_FS_CLUSTER_PAGE_LIMIT) -#define EROFS_PCPUBUF_NR_PAGES Z_EROFS_CLUSTER_MAX_PAGES -#else -#define EROFS_PCPUBUF_NR_PAGES 0 #endif /* !CONFIG_EROFS_FS_ZIP */ /* we strictly follow PAGE_SIZE and no buffer head yet */ @@ -405,24 +402,16 @@ int erofs_namei(struct inode *dir, struct qstr *name, /* dir.c */ extern const struct file_operations erofs_dir_fops; +/* pcpubuf.c */ +void *erofs_get_pcpubuf(unsigned int requiredpages); +void erofs_put_pcpubuf(void *ptr); +int erofs_pcpubuf_growsize(unsigned int nrpages); +void erofs_pcpubuf_init(void); +void erofs_pcpubuf_exit(void); + /* utils.c / zdata.c */ struct page *erofs_allocpage(struct list_head *pool, gfp_t gfp); -#if (EROFS_PCPUBUF_NR_PAGES > 0) -void *erofs_get_pcpubuf(unsigned int pagenr); -#define erofs_put_pcpubuf(buf) do { \ - (void)&(buf); \ - preempt_enable(); \ -} while (0) -#else -static inline void *erofs_get_pcpubuf(unsigned int pagenr) -{ - return ERR_PTR(-EOPNOTSUPP); -} - -#define erofs_put_pcpubuf(buf) do {} while (0) -#endif - #ifdef CONFIG_EROFS_FS_ZIP int erofs_workgroup_put(struct erofs_workgroup *grp); struct erofs_workgroup *erofs_find_workgroup(struct super_block *sb, diff --git a/fs/erofs/pcpubuf.c b/fs/erofs/pcpubuf.c new file mode 100644 index 000000000000..6c885575128a --- /dev/null +++ b/fs/erofs/pcpubuf.c @@ -0,0 +1,148 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) Gao Xiang + * + * For low-latency decompression algorithms (e.g. lz4), reserve consecutive + * per-CPU virtual memory (in pages) in advance to store such inplace I/O + * data if inplace decompression is failed (due to unmet inplace margin for + * example). + */ +#include "internal.h" + +struct erofs_pcpubuf { + raw_spinlock_t lock; + void *ptr; + struct page **pages; + unsigned int nrpages; +}; + +static DEFINE_PER_CPU(struct erofs_pcpubuf, erofs_pcb); + +void *erofs_get_pcpubuf(unsigned int requiredpages) + __acquires(pcb->lock) +{ + struct erofs_pcpubuf *pcb = &get_cpu_var(erofs_pcb); + + raw_spin_lock(&pcb->lock); + /* check if the per-CPU buffer is too small */ + if (requiredpages > pcb->nrpages) { + raw_spin_unlock(&pcb->lock); + put_cpu_var(erofs_pcb); + /* (for sparse checker) pretend pcb->lock is still taken */ + __acquire(pcb->lock); + return NULL; + } + return pcb->ptr; +} + +void erofs_put_pcpubuf(void *ptr) __releases(pcb->lock) +{ + struct erofs_pcpubuf *pcb = &per_cpu(erofs_pcb, smp_processor_id()); + + DBG_BUGON(pcb->ptr != ptr); + raw_spin_unlock(&pcb->lock); + put_cpu_var(erofs_pcb); +} + +/* the next step: support per-CPU page buffers hotplug */ +int erofs_pcpubuf_growsize(unsigned int nrpages) +{ + static DEFINE_MUTEX(pcb_resize_mutex); + static unsigned int pcb_nrpages; + LIST_HEAD(pagepool); + int delta, cpu, ret, i; + + mutex_lock(&pcb_resize_mutex); + delta = nrpages - pcb_nrpages; + ret = 0; + /* avoid shrinking pcpubuf, since no idea how many fses rely on */ + if (delta <= 0) + goto out; + + for_each_possible_cpu(cpu) { + struct erofs_pcpubuf *pcb = &per_cpu(erofs_pcb, cpu); + struct page **pages, **oldpages; + void *ptr, *old_ptr; + + pages = kmalloc_array(nrpages, sizeof(*pages), GFP_KERNEL); + if (!pages) { + ret = -ENOMEM; + break; + } + + for (i = 0; i < nrpages; ++i) { + pages[i] = erofs_allocpage(&pagepool, GFP_KERNEL); + if (!pages[i]) { + ret = -ENOMEM; + oldpages = pages; + goto free_pagearray; + } + } + ptr = vmap(pages, nrpages, VM_MAP, PAGE_KERNEL); + if (!ptr) { + ret = -ENOMEM; + oldpages = pages; + goto free_pagearray; + } + raw_spin_lock(&pcb->lock); + old_ptr = pcb->ptr; + pcb->ptr = ptr; + oldpages = pcb->pages; + pcb->pages = pages; + i = pcb->nrpages; + pcb->nrpages = nrpages; + raw_spin_unlock(&pcb->lock); + + if (!oldpages) { + DBG_BUGON(old_ptr); + continue; + } + + if (old_ptr) + vunmap(old_ptr); +free_pagearray: + while (i) + list_add(&oldpages[--i]->lru, &pagepool); + kfree(oldpages); + if (ret) + break; + } + pcb_nrpages = nrpages; + put_pages_list(&pagepool); +out: + mutex_unlock(&pcb_resize_mutex); + return ret; +} + +void erofs_pcpubuf_init(void) +{ + int cpu; + + for_each_possible_cpu(cpu) { + struct erofs_pcpubuf *pcb = &per_cpu(erofs_pcb, cpu); + + raw_spin_lock_init(&pcb->lock); + } +} + +void erofs_pcpubuf_exit(void) +{ + int cpu, i; + + for_each_possible_cpu(cpu) { + struct erofs_pcpubuf *pcb = &per_cpu(erofs_pcb, cpu); + + if (pcb->ptr) { + vunmap(pcb->ptr); + pcb->ptr = NULL; + } + if (!pcb->pages) + continue; + + for (i = 0; i < pcb->nrpages; ++i) + if (pcb->pages[i]) + put_page(pcb->pages[i]); + kfree(pcb->pages); + pcb->pages = NULL; + } +} diff --git a/fs/erofs/super.c b/fs/erofs/super.c index b641658e772f..bbf3bbd908e0 100644 --- a/fs/erofs/super.c +++ b/fs/erofs/super.c @@ -655,6 +655,7 @@ static int __init erofs_module_init(void) if (err) goto shrinker_err; + erofs_pcpubuf_init(); err = z_erofs_init_zip_subsystem(); if (err) goto zip_err; @@ -684,6 +685,7 @@ static void __exit erofs_module_exit(void) /* Ensure all RCU free inodes are safe before cache is destroyed. */ rcu_barrier(); kmem_cache_destroy(erofs_inode_cachep); + erofs_pcpubuf_exit(); } /* get filesystem statistics */ diff --git a/fs/erofs/utils.c b/fs/erofs/utils.c index de9986d2f82f..6758c5b19f7c 100644 --- a/fs/erofs/utils.c +++ b/fs/erofs/utils.c @@ -21,18 +21,6 @@ struct page *erofs_allocpage(struct list_head *pool, gfp_t gfp) return page; } -#if (EROFS_PCPUBUF_NR_PAGES > 0) -static struct { - u8 data[PAGE_SIZE * EROFS_PCPUBUF_NR_PAGES]; -} ____cacheline_aligned_in_smp erofs_pcpubuf[NR_CPUS]; - -void *erofs_get_pcpubuf(unsigned int pagenr) -{ - preempt_disable(); - return &erofs_pcpubuf[smp_processor_id()].data[pagenr * PAGE_SIZE]; -} -#endif - #ifdef CONFIG_EROFS_FS_ZIP /* global shrink count (for all mounted EROFS instances) */ static atomic_long_t erofs_global_shrink_cnt; 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