cregit-Linux how code gets into the kernel

Release 4.10 fs/squashfs/decompressor_multi.c

Directory: fs/squashfs
 *  Copyright (c) 2013
 *  Minchan Kim <>
 *  This work is licensed under the terms of the GNU GPL, version 2. See
 *  the COPYING file in the top-level directory.
#include <linux/types.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/buffer_head.h>
#include <linux/sched.h>
#include <linux/wait.h>
#include <linux/cpumask.h>

#include "squashfs_fs.h"
#include "squashfs_fs_sb.h"
#include "decompressor.h"
#include "squashfs.h"

 * This file implements multi-threaded decompression in the
 * decompressor framework

 * The reason that multiply two is that a CPU can request new I/O
 * while it is waiting previous request.

#define MAX_DECOMPRESSOR	(num_online_cpus() * 2)

int squashfs_max_decompressors(void) { return MAX_DECOMPRESSOR; }


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struct squashfs_stream { void *comp_opts; struct list_head strm_list; struct mutex mutex; int avail_decomp; wait_queue_head_t wait; }; struct decomp_stream { void *stream; struct list_head list; };
static void put_decomp_stream(struct decomp_stream *decomp_strm, struct squashfs_stream *stream) { mutex_lock(&stream->mutex); list_add(&decomp_strm->list, &stream->strm_list); mutex_unlock(&stream->mutex); wake_up(&stream->wait); }


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void *squashfs_decompressor_create(struct squashfs_sb_info *msblk, void *comp_opts) { struct squashfs_stream *stream; struct decomp_stream *decomp_strm = NULL; int err = -ENOMEM; stream = kzalloc(sizeof(*stream), GFP_KERNEL); if (!stream) goto out; stream->comp_opts = comp_opts; mutex_init(&stream->mutex); INIT_LIST_HEAD(&stream->strm_list); init_waitqueue_head(&stream->wait); /* * We should have a decompressor at least as default * so if we fail to allocate new decompressor dynamically, * we could always fall back to default decompressor and * file system works. */ decomp_strm = kmalloc(sizeof(*decomp_strm), GFP_KERNEL); if (!decomp_strm) goto out; decomp_strm->stream = msblk->decompressor->init(msblk, stream->comp_opts); if (IS_ERR(decomp_strm->stream)) { err = PTR_ERR(decomp_strm->stream); goto out; } list_add(&decomp_strm->list, &stream->strm_list); stream->avail_decomp = 1; return stream; out: kfree(decomp_strm); kfree(stream); return ERR_PTR(err); }


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void squashfs_decompressor_destroy(struct squashfs_sb_info *msblk) { struct squashfs_stream *stream = msblk->stream; if (stream) { struct decomp_stream *decomp_strm; while (!list_empty(&stream->strm_list)) { decomp_strm = list_entry(stream->strm_list.prev, struct decomp_stream, list); list_del(&decomp_strm->list); msblk->decompressor->free(decomp_strm->stream); kfree(decomp_strm); stream->avail_decomp--; } WARN_ON(stream->avail_decomp); kfree(stream->comp_opts); kfree(stream); } }


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phillip lougherphillip lougher10.93%150.00%

static struct decomp_stream *get_decomp_stream(struct squashfs_sb_info *msblk, struct squashfs_stream *stream) { struct decomp_stream *decomp_strm; while (1) { mutex_lock(&stream->mutex); /* There is available decomp_stream */ if (!list_empty(&stream->strm_list)) { decomp_strm = list_entry(stream->strm_list.prev, struct decomp_stream, list); list_del(&decomp_strm->list); mutex_unlock(&stream->mutex); break; } /* * If there is no available decomp and already full, * let's wait for releasing decomp from other users. */ if (stream->avail_decomp >= MAX_DECOMPRESSOR) goto wait; /* Let's allocate new decomp */ decomp_strm = kmalloc(sizeof(*decomp_strm), GFP_KERNEL); if (!decomp_strm) goto wait; decomp_strm->stream = msblk->decompressor->init(msblk, stream->comp_opts); if (IS_ERR(decomp_strm->stream)) { kfree(decomp_strm); goto wait; } stream->avail_decomp++; WARN_ON(stream->avail_decomp > MAX_DECOMPRESSOR); mutex_unlock(&stream->mutex); break; wait: /* * If system memory is tough, let's for other's * releasing instead of hurting VM because it could * make page cache thrashing. */ mutex_unlock(&stream->mutex); wait_event(stream->wait, !list_empty(&stream->strm_list)); } return decomp_strm; }


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int squashfs_decompress(struct squashfs_sb_info *msblk, struct buffer_head **bh, int b, int offset, int length, struct squashfs_page_actor *output) { int res; struct squashfs_stream *stream = msblk->stream; struct decomp_stream *decomp_stream = get_decomp_stream(msblk, stream); res = msblk->decompressor->decompress(msblk, decomp_stream->stream, bh, b, offset, length, output); put_decomp_stream(decomp_stream, stream); if (res < 0) ERROR("%s decompression failed, data probably corrupt\n", msblk->decompressor->name); return res; }


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Overall Contributors

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Directory: fs/squashfs
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