fs/erofs/decompressor_deflate.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 #include <linux/zlib.h>
   3 #include "compress.h"
   4
   5 struct z_erofs_deflate {
   6         struct z_erofs_deflate *next;
   7         struct z_stream_s z;
   8         u8 bounce[PAGE_SIZE];
   9 };
  10
  11 static DEFINE_SPINLOCK(z_erofs_deflate_lock);
  12 static unsigned int z_erofs_deflate_nstrms, z_erofs_deflate_avail_strms;
  13 static struct z_erofs_deflate *z_erofs_deflate_head;
  14 static DECLARE_WAIT_QUEUE_HEAD(z_erofs_deflate_wq);
  15
  16 module_param_named(deflate_streams, z_erofs_deflate_nstrms, uint, 0444);
  17
  18 static void z_erofs_deflate_exit(void)
  19 {
  20         /* there should be no running fs instance */
  21         while (z_erofs_deflate_avail_strms) {
  22                 struct z_erofs_deflate *strm;
  23
  24                 spin_lock(&z_erofs_deflate_lock);
  25                 strm = z_erofs_deflate_head;
  26                 if (!strm) {
  27                         spin_unlock(&z_erofs_deflate_lock);
  28                         continue;
  29                 }
  30                 z_erofs_deflate_head = NULL;
  31                 spin_unlock(&z_erofs_deflate_lock);
  32
  33                 while (strm) {
  34                         struct z_erofs_deflate *n = strm->next;
  35
  36                         vfree(strm->z.workspace);
  37                         kfree(strm);
  38                         --z_erofs_deflate_avail_strms;
  39                         strm = n;
  40                 }
  41         }
  42 }
  43
  44 static int __init z_erofs_deflate_init(void)
  45 {
  46         /* by default, use # of possible CPUs instead */
  47         if (!z_erofs_deflate_nstrms)
  48                 z_erofs_deflate_nstrms = num_possible_cpus();
  49         return 0;
  50 }
  51
  52 static int z_erofs_load_deflate_config(struct super_block *sb,
  53                         struct erofs_super_block *dsb, void *data, int size)
  54 {
  55         struct z_erofs_deflate_cfgs *dfl = data;
  56         static DEFINE_MUTEX(deflate_resize_mutex);
  57         static bool inited;
  58
  59         if (!dfl || size < sizeof(struct z_erofs_deflate_cfgs)) {
  60                 erofs_err(sb, "invalid deflate cfgs, size=%u", size);
  61                 return -EINVAL;
  62         }
  63
  64         if (dfl->windowbits > MAX_WBITS) {
  65                 erofs_err(sb, "unsupported windowbits %u", dfl->windowbits);
  66                 return -EOPNOTSUPP;
  67         }
  68         mutex_lock(&deflate_resize_mutex);
  69         if (!inited) {
  70                 for (; z_erofs_deflate_avail_strms < z_erofs_deflate_nstrms;
  71                      ++z_erofs_deflate_avail_strms) {
  72                         struct z_erofs_deflate *strm;
  73
  74                         strm = kzalloc(sizeof(*strm), GFP_KERNEL);
  75                         if (!strm)
  76                                 goto failed;
  77                         /* XXX: in-kernel zlib cannot customize windowbits */
  78                         strm->z.workspace = vmalloc(zlib_inflate_workspacesize());
  79                         if (!strm->z.workspace) {
  80                                 kfree(strm);
  81                                 goto failed;
  82                         }
  83
  84                         spin_lock(&z_erofs_deflate_lock);
  85                         strm->next = z_erofs_deflate_head;
  86                         z_erofs_deflate_head = strm;
  87                         spin_unlock(&z_erofs_deflate_lock);
  88                 }
  89                 inited = true;
  90         }
  91         mutex_unlock(&deflate_resize_mutex);
  92         erofs_info(sb, "EXPERIMENTAL DEFLATE feature in use. Use at your own risk!");
  93         return 0;
  94 failed:
  95         mutex_unlock(&deflate_resize_mutex);
  96         z_erofs_deflate_exit();
  97         return -ENOMEM;
  98 }
  99
 100 static int z_erofs_deflate_decompress(struct z_erofs_decompress_req *rq,
 101                                       struct page **pgpl)
 102 {
 103         struct super_block *sb = rq->sb;
 104         struct z_erofs_stream_dctx dctx = {
 105                 .rq = rq,
 106                 .inpages = PAGE_ALIGN(rq->inputsize) >> PAGE_SHIFT,
 107                 .outpages = PAGE_ALIGN(rq->pageofs_out + rq->outputsize)
 108                                 >> PAGE_SHIFT,
 109                 .no = -1, .ni = 0,
 110         };
 111         struct z_erofs_deflate *strm;
 112         int zerr, err;
 113
 114         /* 1. get the exact DEFLATE compressed size */
 115         dctx.kin = kmap_local_page(*rq->in);
 116         err = z_erofs_fixup_insize(rq, dctx.kin + rq->pageofs_in,
 117                         min(rq->inputsize, sb->s_blocksize - rq->pageofs_in));
 118         if (err) {
 119                 kunmap_local(dctx.kin);
 120                 return err;
 121         }
 122
 123         /* 2. get an available DEFLATE context */
 124 again:
 125         spin_lock(&z_erofs_deflate_lock);
 126         strm = z_erofs_deflate_head;
 127         if (!strm) {
 128                 spin_unlock(&z_erofs_deflate_lock);
 129                 wait_event(z_erofs_deflate_wq, READ_ONCE(z_erofs_deflate_head));
 130                 goto again;
 131         }
 132         z_erofs_deflate_head = strm->next;
 133         spin_unlock(&z_erofs_deflate_lock);
 134
 135         /* 3. multi-call decompress */
 136         zerr = zlib_inflateInit2(&strm->z, -MAX_WBITS);
 137         if (zerr != Z_OK) {
 138                 err = -EIO;
 139                 goto failed_zinit;
 140         }
 141
 142         rq->fillgaps = true;    /* DEFLATE doesn't support NULL output buffer */
 143         strm->z.avail_in = min(rq->inputsize, PAGE_SIZE - rq->pageofs_in);
 144         rq->inputsize -= strm->z.avail_in;
 145         strm->z.next_in = dctx.kin + rq->pageofs_in;
 146         strm->z.avail_out = 0;
 147         dctx.bounce = strm->bounce;
 148
 149         while (1) {
 150                 dctx.avail_out = strm->z.avail_out;
 151                 dctx.inbuf_sz = strm->z.avail_in;
 152                 err = z_erofs_stream_switch_bufs(&dctx,
 153                                         (void **)&strm->z.next_out,
 154                                         (void **)&strm->z.next_in, pgpl);
 155                 if (err)
 156                         break;
 157                 strm->z.avail_out = dctx.avail_out;
 158                 strm->z.avail_in = dctx.inbuf_sz;
 159
 160                 zerr = zlib_inflate(&strm->z, Z_SYNC_FLUSH);
 161                 if (zerr != Z_OK || !(rq->outputsize + strm->z.avail_out)) {
 162                         if (zerr == Z_OK && rq->partial_decoding)
 163                                 break;
 164                         if (zerr == Z_STREAM_END && !rq->outputsize)
 165                                 break;
 166                         erofs_err(sb, "failed to decompress %d in[%u] out[%u]",
 167                                   zerr, rq->inputsize, rq->outputsize);
 168                         err = -EFSCORRUPTED;
 169                         break;
 170                 }
 171         }
 172         if (zlib_inflateEnd(&strm->z) != Z_OK && !err)
 173                 err = -EIO;
 174         if (dctx.kout)
 175                 kunmap_local(dctx.kout);
 176 failed_zinit:
 177         kunmap_local(dctx.kin);
 178         /* 4. push back DEFLATE stream context to the global list */
 179         spin_lock(&z_erofs_deflate_lock);
 180         strm->next = z_erofs_deflate_head;
 181         z_erofs_deflate_head = strm;
 182         spin_unlock(&z_erofs_deflate_lock);
 183         wake_up(&z_erofs_deflate_wq);
 184         return err;
 185 }
 186
 187 const struct z_erofs_decompressor z_erofs_deflate_decomp = {
 188         .config = z_erofs_load_deflate_config,
 189         .decompress = z_erofs_deflate_decompress,
 190         .init = z_erofs_deflate_init,
 191         .exit = z_erofs_deflate_exit,
 192         .name = "deflate",
 193 };