Currently, fsck.erofs extracts files synchronously. When decompressing heavily packed images (like LZ4HC with 4K pclusters), the main thread spends the majority of its time blocked on a combination of synchronous vfs_write() syscalls and LZ4_decompress_safe(), bottlenecking overall extraction speed.
This patch introduces a scalable, multi-threaded decompression framework using the existing erofs_workqueue infrastructure to decouple compute from the main thread's I/O. To prevent massive scheduling overhead (futex contention) where worker threads spend more CPU time waking up than actually decompressing small 4KB clusters, this implementation introduces a batching context. The main thread collects an array of sequential pclusters (temporarily hard- capped at Z_EROFS_PCLUSTER_BATCH_SIZE = 32) before submitting a single erofs_work unit. Key details of this implementation: - The worker pool is dynamically sized based on available system CPUs. - Decompression tasks take strict ownership of the raw and output buffers (safely tracking memory via a `free_out` flag) to prevent data races and memory leaks. - Output buffers are explicitly zero-initialized via calloc() to prevent trailing garbage bytes from leaking into extracted files. - Tail-end packed fragments are processed synchronously by the main thread, as their minimal overhead does not benefit from asynchronous offloading. Signed-off-by: Nithurshen <[email protected]> --- fsck/main.c | 239 ++++++++++++++++++--------------------- include/erofs/internal.h | 19 +++- include/erofs/lock.h | 22 ++++ lib/data.c | 207 +++++++++++++++++++++++---------- 4 files changed, 298 insertions(+), 189 deletions(-) diff --git a/fsck/main.c b/fsck/main.c index 16cc627..de6ab4d 100644 --- a/fsck/main.c +++ b/fsck/main.c @@ -8,14 +8,18 @@ #include <time.h> #include <utime.h> #include <unistd.h> +#include "erofs/lock.h" #include <sys/stat.h> #include "erofs/print.h" #include "erofs/decompress.h" #include "erofs/dir.h" #include "erofs/xattr.h" +#include "erofs/workqueue.h" #include "../lib/compressor.h" #include "../lib/liberofs_compress.h" +extern struct erofs_workqueue erofs_wq; + static int erofsfsck_check_inode(erofs_nid_t pnid, erofs_nid_t nid); struct erofsfsck_dirstack { @@ -505,135 +509,95 @@ out: static int erofs_verify_inode_data(struct erofs_inode *inode, int outfd) { - struct erofs_map_blocks map = { - .buf = __EROFS_BUF_INITIALIZER, - }; - bool needdecode = fsckcfg.check_decomp && !erofs_is_packed_inode(inode); - int ret = 0; - bool compressed; - erofs_off_t pos = 0; - u64 pchunk_len = 0; - unsigned int raw_size = 0, buffer_size = 0; - char *raw = NULL, *buffer = NULL; - - erofs_dbg("verify data chunk of nid(%llu): type(%d)", - inode->nid | 0ULL, inode->datalayout); - - compressed = erofs_inode_is_data_compressed(inode->datalayout); - while (pos < inode->i_size) { - unsigned int alloc_rawsize; - - map.m_la = pos; - ret = erofs_map_blocks(inode, &map, EROFS_GET_BLOCKS_FIEMAP); - if (ret) - goto out; - - if (!compressed && map.m_llen != map.m_plen) { - erofs_err("broken chunk length m_la %" PRIu64 " m_llen %" PRIu64 " m_plen %" PRIu64, - map.m_la, map.m_llen, map.m_plen); - ret = -EFSCORRUPTED; - goto out; - } - - /* the last lcluster can be divided into 3 parts */ - if (map.m_la + map.m_llen > inode->i_size) - map.m_llen = inode->i_size - map.m_la; - - pchunk_len += map.m_plen; - pos += map.m_llen; - - /* should skip decomp? */ - if (map.m_la >= inode->i_size || !needdecode) - continue; - - if (outfd >= 0 && !(map.m_flags & EROFS_MAP_MAPPED)) { - ret = lseek(outfd, map.m_llen, SEEK_CUR); - if (ret < 0) { - ret = -errno; - goto out; - } - continue; - } - - if (map.m_plen > Z_EROFS_PCLUSTER_MAX_SIZE) { - if (compressed && !(map.m_flags & __EROFS_MAP_FRAGMENT)) { - erofs_err("invalid pcluster size %" PRIu64 " @ offset %" PRIu64 " of nid %" PRIu64, - map.m_plen, map.m_la, - inode->nid | 0ULL); - ret = -EFSCORRUPTED; - goto out; - } - alloc_rawsize = Z_EROFS_PCLUSTER_MAX_SIZE; - } else { - alloc_rawsize = map.m_plen; - } - - if (alloc_rawsize > raw_size) { - char *newraw = realloc(raw, alloc_rawsize); + struct erofs_map_blocks map = { .buf = __EROFS_BUF_INITIALIZER }; + bool needdecode = fsckcfg.check_decomp && !erofs_is_packed_inode(inode); + int ret = 0; + bool compressed = erofs_inode_is_data_compressed(inode->datalayout); + erofs_off_t pos = 0; + u64 pchunk_len = 0; + + struct z_erofs_read_ctx ctx = { + .pending_tasks = 0, + .final_err = 0, + .outfd = outfd, + .free_out = true, + .current_task = NULL + }; + erofs_mutex_init(&ctx.lock); + erofs_cond_init(&ctx.cond); + + erofs_dbg("verify data chunk of nid(%llu): type(%d)", inode->nid | 0ULL, inode->datalayout); + + while (pos < inode->i_size) { + map.m_la = pos; + ret = erofs_map_blocks(inode, &map, EROFS_GET_BLOCKS_FIEMAP); + if (ret) goto out; + + if (map.m_la + map.m_llen > inode->i_size) + map.m_llen = inode->i_size - map.m_la; + + pchunk_len += map.m_plen; + pos += map.m_llen; + + if (map.m_la >= inode->i_size || !needdecode) + continue; + + if (outfd >= 0 && !(map.m_flags & EROFS_MAP_MAPPED)) { + ret = lseek(outfd, map.m_llen, SEEK_CUR); + if (ret < 0) { + ret = -errno; + goto out; + } + continue; + } + + if (compressed) { + char *raw = malloc(map.m_plen); + size_t buffer_size = map.m_llen > erofs_blksiz(inode->sbi) ? map.m_llen : erofs_blksiz(inode->sbi); + char *buffer = calloc(1, buffer_size); + + if (!raw || !buffer) { + free(raw); free(buffer); + ret = -ENOMEM; + goto out; + } + + ret = z_erofs_read_one_data(inode, &map, raw, buffer, 0, map.m_llen, false, map.m_la, &ctx); + if (ret) { + /* DO NOT free(raw) or free(buffer) here. z_erofs_read_one_data took ownership! */ + goto out; + } + } else { + char *raw = calloc(1, map.m_llen); + ret = erofs_read_one_data(inode, &map, raw, 0, map.m_llen); + if (ret >= 0 && outfd >= 0) + pwrite(outfd, raw, map.m_llen, map.m_la); + free(raw); + if (ret) goto out; + } + } + z_erofs_read_ctx_enqueue(&ctx); - if (!newraw) { - ret = -ENOMEM; - goto out; - } - raw = newraw; - raw_size = alloc_rawsize; - } - - if (compressed) { - if (map.m_llen > buffer_size) { - char *newbuffer; - - buffer_size = map.m_llen; - newbuffer = realloc(buffer, buffer_size); - if (!newbuffer) { - ret = -ENOMEM; - goto out; - } - buffer = newbuffer; - } - ret = z_erofs_read_one_data(inode, &map, raw, buffer, - 0, map.m_llen, false); - if (ret) - goto out; - - if (outfd >= 0 && write(outfd, buffer, map.m_llen) < 0) - goto fail_eio; - } else { - u64 p = 0; - - do { - u64 count = min_t(u64, alloc_rawsize, - map.m_llen); - - ret = erofs_read_one_data(inode, &map, raw, p, count); - if (ret) - goto out; - - if (outfd >= 0 && write(outfd, raw, count) < 0) - goto fail_eio; - map.m_llen -= count; - p += count; - } while (map.m_llen); - } - } - - if (fsckcfg.print_comp_ratio) { - if (!erofs_is_packed_inode(inode)) - fsckcfg.logical_blocks += BLK_ROUND_UP(inode->sbi, inode->i_size); - fsckcfg.physical_blocks += BLK_ROUND_UP(inode->sbi, pchunk_len); - } out: - if (raw) - free(raw); - if (buffer) - free(buffer); - return ret < 0 ? ret : 0; - -fail_eio: - erofs_err("I/O error occurred when verifying data chunk @ nid %llu", - inode->nid | 0ULL); - ret = -EIO; - goto out; + erofs_mutex_lock(&ctx.lock); + while (ctx.pending_tasks > 0) + erofs_cond_wait(&ctx.cond, &ctx.lock); + if (ctx.final_err < 0 && ret >= 0) + ret = ctx.final_err; + erofs_mutex_unlock(&ctx.lock); + + if (fsckcfg.print_comp_ratio) { + if (!erofs_is_packed_inode(inode)) + fsckcfg.logical_blocks += BLK_ROUND_UP(inode->sbi, inode->i_size); + fsckcfg.physical_blocks += BLK_ROUND_UP(inode->sbi, pchunk_len); + } + + if (outfd >= 0 && ret >= 0) + ftruncate(outfd, inode->i_size); + + erofs_mutex_destroy(&ctx.lock); + erofs_cond_destroy(&ctx.cond); + return ret < 0 ? ret : 0; } static inline int erofs_extract_dir(struct erofs_inode *inode) @@ -1043,9 +1007,19 @@ int erofsfsck_fuzz_one(int argc, char *argv[]) int main(int argc, char *argv[]) #endif { + int err; +#ifdef EROFS_MT_ENABLED + int workers; +#endif - erofs_init_configure(); + erofs_init_configure(); + +#ifdef EROFS_MT_ENABLED + workers = sysconf(_SC_NPROCESSORS_ONLN); + if (workers < 1) workers = 1; + erofs_alloc_workqueue(&erofs_wq, workers, 256, NULL, NULL); +#endif fsckcfg.physical_blocks = 0; fsckcfg.logical_blocks = 0; @@ -1179,9 +1153,12 @@ exit_put_super: exit_dev_close: erofs_dev_close(&g_sbi); exit: - erofs_blob_closeall(&g_sbi); - erofs_exit_configure(); - return err ? 1 : 0; + erofs_blob_closeall(&g_sbi); + erofs_exit_configure(); +#ifdef EROFS_MT_ENABLED + erofs_destroy_workqueue(&erofs_wq); +#endif + return err ? 1 : 0; } #ifdef FUZZING diff --git a/include/erofs/internal.h b/include/erofs/internal.h index 671880f..63fd3bf 100644 --- a/include/erofs/internal.h +++ b/include/erofs/internal.h @@ -25,6 +25,7 @@ typedef unsigned short umode_t; #ifdef HAVE_PTHREAD_H #include <pthread.h> #endif +#include <erofs/lock.h> #include <stdlib.h> #include <string.h> #include "atomic.h" @@ -62,6 +63,7 @@ struct erofs_buf { #define erofs_pos(sbi, nr) ((erofs_off_t)(nr) << (sbi)->blkszbits) #define BLK_ROUND_UP(sbi, addr) \ (roundup(addr, erofs_blksiz(sbi)) >> (sbi)->blkszbits) +#define Z_EROFS_PCLUSTER_BATCH_SIZE 32 struct erofs_buffer_head; struct erofs_bufmgr; @@ -442,6 +444,20 @@ struct z_erofs_paramset { char *extraopts; }; +struct z_erofs_decompress_task; + +struct z_erofs_read_ctx { + erofs_mutex_t lock; + erofs_cond_t cond; + int pending_tasks; + int final_err; + int outfd; + bool free_out; + struct z_erofs_decompress_task *current_task; +}; + +void z_erofs_read_ctx_enqueue(struct z_erofs_read_ctx *ctx); + int liberofs_global_init(void); void liberofs_global_exit(void); @@ -478,7 +494,8 @@ int erofs_read_one_data(struct erofs_inode *inode, struct erofs_map_blocks *map, char *buffer, u64 offset, size_t len); int z_erofs_read_one_data(struct erofs_inode *inode, struct erofs_map_blocks *map, char *raw, char *buffer, - erofs_off_t skip, erofs_off_t length, bool trimmed); + erofs_off_t skip, erofs_off_t length, bool trimmed, + erofs_off_t out_offset, struct z_erofs_read_ctx *ctx); void *erofs_read_metadata(struct erofs_sb_info *sbi, erofs_nid_t nid, erofs_off_t *offset, int *lengthp); int z_erofs_parse_cfgs(struct erofs_sb_info *sbi, struct erofs_super_block *dsb); diff --git a/include/erofs/lock.h b/include/erofs/lock.h index c6e3093..a2e1b60 100644 --- a/include/erofs/lock.h +++ b/include/erofs/lock.h @@ -15,6 +15,7 @@ static inline void erofs_mutex_init(erofs_mutex_t *lock) } #define erofs_mutex_lock pthread_mutex_lock #define erofs_mutex_unlock pthread_mutex_unlock +#define erofs_mutex_destroy pthread_mutex_destroy #define EROFS_DEFINE_MUTEX(lock) \ erofs_mutex_t lock = PTHREAD_MUTEX_INITIALIZER @@ -29,12 +30,25 @@ static inline void erofs_init_rwsem(erofs_rwsem_t *lock) #define erofs_down_write pthread_rwlock_wrlock #define erofs_up_read pthread_rwlock_unlock #define erofs_up_write pthread_rwlock_unlock + +typedef pthread_cond_t erofs_cond_t; + +static inline void erofs_cond_init(erofs_cond_t *cond) +{ + pthread_cond_init(cond, NULL); +} +#define erofs_cond_wait pthread_cond_wait +#define erofs_cond_signal pthread_cond_signal +#define erofs_cond_broadcast pthread_cond_broadcast +#define erofs_cond_destroy pthread_cond_destroy + #else typedef struct {} erofs_mutex_t; static inline void erofs_mutex_init(erofs_mutex_t *lock) {} static inline void erofs_mutex_lock(erofs_mutex_t *lock) {} static inline void erofs_mutex_unlock(erofs_mutex_t *lock) {} +static inline void erofs_mutex_destroy(erofs_mutex_t *lock) {} #define EROFS_DEFINE_MUTEX(lock) \ erofs_mutex_t lock = {} @@ -46,5 +60,13 @@ static inline void erofs_down_write(erofs_rwsem_t *lock) {} static inline void erofs_up_read(erofs_rwsem_t *lock) {} static inline void erofs_up_write(erofs_rwsem_t *lock) {} +typedef struct {} erofs_cond_t; + +static inline void erofs_cond_init(erofs_cond_t *cond) {} +static inline int erofs_cond_wait(erofs_cond_t *cond, erofs_mutex_t *mutex) { return 0; } +static inline int erofs_cond_signal(erofs_cond_t *cond) { return 0; } +static inline int erofs_cond_broadcast(erofs_cond_t *cond) { return 0; } +static inline int erofs_cond_destroy(erofs_cond_t *cond) { return 0; } + #endif #endif diff --git a/lib/data.c b/lib/data.c index 6fd1389..26fdb43 100644 --- a/lib/data.c +++ b/lib/data.c @@ -9,6 +9,68 @@ #include "erofs/trace.h" #include "erofs/decompress.h" #include "liberofs_fragments.h" +#include "erofs/workqueue.h" +#include "erofs/lock.h" + +struct erofs_workqueue erofs_wq; + +struct z_erofs_decompress_task { + struct erofs_work work; + struct z_erofs_read_ctx *ctx; + struct z_erofs_decompress_req reqs[Z_EROFS_PCLUSTER_BATCH_SIZE]; + char *raw_bufs[Z_EROFS_PCLUSTER_BATCH_SIZE]; + char *out_bufs[Z_EROFS_PCLUSTER_BATCH_SIZE]; + erofs_off_t out_offsets[Z_EROFS_PCLUSTER_BATCH_SIZE]; + unsigned int out_lengths[Z_EROFS_PCLUSTER_BATCH_SIZE]; + unsigned int nr_reqs; +}; + +static void z_erofs_decompress_worker(struct erofs_work *work, void *tlsp) +{ + struct z_erofs_decompress_task *task = (struct z_erofs_decompress_task *)work; + struct z_erofs_read_ctx *ctx = task->ctx; + int i, ret = 0, first_err = 0; + + for (i = 0; i < task->nr_reqs; ++i) { + ret = z_erofs_decompress(&task->reqs[i]); + + if (ret >= 0 && ctx && ctx->outfd >= 0) { + if (pwrite(ctx->outfd, task->out_bufs[i], + task->out_lengths[i], task->out_offsets[i]) < 0) + ret = -errno; + } + + if (ret < 0 && first_err == 0) + first_err = ret; + + free(task->raw_bufs[i]); + if (ctx && ctx->free_out) + free(task->out_bufs[i]); + } + + if (ctx) { + erofs_mutex_lock(&ctx->lock); + if (first_err < 0 && ctx->final_err == 0) + ctx->final_err = first_err; + ctx->pending_tasks--; + if (ctx->pending_tasks == 0) + erofs_cond_signal(&ctx->cond); + erofs_mutex_unlock(&ctx->lock); + } + free(task); +} + +void z_erofs_read_ctx_enqueue(struct z_erofs_read_ctx *ctx) +{ + if (ctx && ctx->current_task) { +#ifdef EROFS_MT_ENABLED + erofs_queue_work(&erofs_wq, &ctx->current_task->work); +#else + z_erofs_decompress_worker(&ctx->current_task->work, NULL); +#endif + ctx->current_task = NULL; + } +} void *erofs_bread(struct erofs_buf *buf, erofs_off_t offset, bool need_kmap) { @@ -277,7 +339,8 @@ static int erofs_read_raw_data(struct erofs_inode *inode, char *buffer, int z_erofs_read_one_data(struct erofs_inode *inode, struct erofs_map_blocks *map, char *raw, char *buffer, - erofs_off_t skip, erofs_off_t length, bool trimmed) + erofs_off_t skip, erofs_off_t length, bool trimmed, + erofs_off_t out_offset, struct z_erofs_read_ctx *ctx) { struct erofs_sb_info *sbi = inode->sbi; struct erofs_map_dev mdev; @@ -285,77 +348,101 @@ int z_erofs_read_one_data(struct erofs_inode *inode, if (map->m_flags & __EROFS_MAP_FRAGMENT) { if (__erofs_unlikely(inode->nid == sbi->packed_nid)) { - erofs_err("fragment should not exist in the packed inode %llu", - sbi->packed_nid | 0ULL); - return -EFSCORRUPTED; + ret = -EFSCORRUPTED; + goto err_out; } - return erofs_packedfile_read(sbi, buffer, length - skip, - inode->fragmentoff + skip); + ret = erofs_packedfile_read(sbi, buffer, length - skip, + inode->fragmentoff + skip); + + if (ret >= 0 && ctx && ctx->outfd >= 0) { + if (pwrite(ctx->outfd, buffer, length - skip, out_offset) < 0) + ret = -errno; + } + goto err_out; } - /* no device id here, thus it will always succeed */ - mdev = (struct erofs_map_dev) { - .m_pa = map->m_pa, - }; + mdev = (struct erofs_map_dev) { .m_pa = map->m_pa }; ret = erofs_map_dev(sbi, &mdev); - if (ret) { - DBG_BUGON(1); - return ret; - } + if (ret) goto err_out; ret = erofs_dev_read(sbi, mdev.m_deviceid, raw, mdev.m_pa, map->m_plen); - if (ret < 0) - return ret; + if (ret < 0) goto err_out; + + struct z_erofs_decompress_task *task = ctx->current_task; + if (!task) { + task = calloc(1, sizeof(*task)); + task->ctx = ctx; + task->work.fn = z_erofs_decompress_worker; + ctx->current_task = task; + + erofs_mutex_lock(&ctx->lock); + ctx->pending_tasks++; + erofs_mutex_unlock(&ctx->lock); + } - ret = z_erofs_decompress(&(struct z_erofs_decompress_req) { - .sbi = sbi, - .in = raw, - .out = buffer, - .decodedskip = skip, - .interlaced_offset = - map->m_algorithmformat == Z_EROFS_COMPRESSION_INTERLACED ? - erofs_blkoff(sbi, map->m_la) : 0, - .inputsize = map->m_plen, - .decodedlength = length, - .alg = map->m_algorithmformat, - .partial_decoding = trimmed ? true : - !(map->m_flags & EROFS_MAP_FULL_MAPPED) || - (map->m_flags & EROFS_MAP_PARTIAL_REF), - }); - if (ret < 0) - return ret; + int idx = task->nr_reqs++; + task->reqs[idx] = (struct z_erofs_decompress_req) { + .sbi = sbi, + .in = raw, + .out = buffer, + .decodedskip = skip, + .interlaced_offset = + map->m_algorithmformat == Z_EROFS_COMPRESSION_INTERLACED ? + erofs_blkoff(sbi, map->m_la) : 0, + .inputsize = map->m_plen, + .decodedlength = length, + .alg = map->m_algorithmformat, + .partial_decoding = trimmed ? true : + !(map->m_flags & EROFS_MAP_FULL_MAPPED) || + (map->m_flags & EROFS_MAP_PARTIAL_REF), + }; + task->raw_bufs[idx] = raw; + task->out_bufs[idx] = buffer; + task->out_offsets[idx] = out_offset; + task->out_lengths[idx] = length; + + if (task->nr_reqs == Z_EROFS_PCLUSTER_BATCH_SIZE) { + z_erofs_read_ctx_enqueue(ctx); + } return 0; + +err_out: + if (ctx && ctx->free_out) free(buffer); + free(raw); + return ret; } static int z_erofs_read_data(struct erofs_inode *inode, char *buffer, - erofs_off_t size, erofs_off_t offset) + erofs_off_t size, erofs_off_t offset) { erofs_off_t end, length, skip; struct erofs_map_blocks map = { .buf = __EROFS_BUF_INITIALIZER, }; bool trimmed; - unsigned int bufsize = 0; - char *raw = NULL; int ret = 0; + struct z_erofs_read_ctx ctx = { + .pending_tasks = 0, + .final_err = 0, + .outfd = -1, + .free_out = false, + .current_task = NULL + }; + erofs_mutex_init(&ctx.lock); + erofs_cond_init(&ctx.cond); + end = offset + size; while (end > offset) { map.m_la = end - 1; ret = z_erofs_map_blocks_iter(inode, &map, 0); - if (ret) - break; + if (ret) break; - /* - * trim to the needed size if the returned extent is quite - * larger than requested, and set up partial flag as well. - */ if (end < map.m_la + map.m_llen) { length = end - map.m_la; trimmed = true; } else { - DBG_BUGON(end != map.m_la + map.m_llen); length = map.m_llen; trimmed = false; } @@ -374,25 +461,31 @@ static int z_erofs_read_data(struct erofs_inode *inode, char *buffer, continue; } - if (map.m_plen > bufsize) { - char *newraw; - - bufsize = map.m_plen; - newraw = realloc(raw, bufsize); - if (!newraw) { - ret = -ENOMEM; - break; - } - raw = newraw; + char *raw = malloc(map.m_plen); + if (!raw) { + ret = -ENOMEM; + break; } ret = z_erofs_read_one_data(inode, &map, raw, - buffer + end - offset, skip, length, trimmed); - if (ret < 0) + buffer + end - offset, skip, length, trimmed, 0, &ctx); + if (ret < 0) { break; + } } - if (raw) - free(raw); + z_erofs_read_ctx_enqueue(&ctx); + + erofs_mutex_lock(&ctx.lock); + while (ctx.pending_tasks > 0) + erofs_cond_wait(&ctx.cond, &ctx.lock); + + if (ctx.final_err < 0 && ret == 0) + ret = ctx.final_err; + + erofs_mutex_unlock(&ctx.lock); + erofs_mutex_destroy(&ctx.lock); + erofs_cond_destroy(&ctx.cond); + return ret < 0 ? ret : 0; } -- 2.52.0
