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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 | /* * linux/fs/ext2/file.c * * Copyright (C) 1992, 1993, 1994 Remy Card (card@masi.ibp.fr) * Laboratoire MASI - Institut Blaise Pascal * Universite Pierre et Marie Curie (Paris VI) * * from * * linux/fs/minix/file.c * * Copyright (C) 1991, 1992 Linus Torvalds * * ext2 fs regular file handling primitives */ #include <asm/segment.h> #include <asm/system.h> #include <linux/errno.h> #include <linux/fs.h> #include <linux/ext2_fs.h> #include <linux/fcntl.h> #include <linux/sched.h> #include <linux/stat.h> #include <linux/locks.h> #define NBUF 32 #define MIN(a,b) (((a)<(b))?(a):(b)) #define MAX(a,b) (((a)>(b))?(a):(b)) #include <linux/fs.h> #include <linux/ext2_fs.h> static int ext2_file_read (struct inode *, struct file *, char *, int); static int ext2_file_write (struct inode *, struct file *, char *, int); static void ext2_release_file (struct inode *, struct file *); /* * We have mostly NULL's here: the current defaults are ok for * the ext2 filesystem. */ static struct file_operations ext2_file_operations = { NULL, /* lseek - default */ ext2_file_read, /* read */ ext2_file_write, /* write */ NULL, /* readdir - bad */ NULL, /* select - default */ ext2_ioctl, /* ioctl */ generic_mmap, /* mmap */ NULL, /* no special open is needed */ ext2_release_file, /* release */ ext2_sync_file /* fsync */ }; struct inode_operations ext2_file_inode_operations = { &ext2_file_operations,/* default file operations */ NULL, /* create */ NULL, /* lookup */ NULL, /* link */ NULL, /* unlink */ NULL, /* symlink */ NULL, /* mkdir */ NULL, /* rmdir */ NULL, /* mknod */ NULL, /* rename */ NULL, /* readlink */ NULL, /* follow_link */ ext2_bmap, /* bmap */ ext2_truncate, /* truncate */ ext2_permission /* permission */ }; static int ext2_file_read (struct inode * inode, struct file * filp, char * buf, int count) { int read, left, chars; int block, blocks, offset; int bhrequest, uptodate; struct buffer_head ** bhb, ** bhe; struct buffer_head * bhreq[NBUF]; struct buffer_head * buflist[NBUF]; struct super_block * sb; unsigned int size; int err; if (!inode) { printk ("ext2_file_read: inode = NULL\n"); return -EINVAL; } sb = inode->i_sb; if (!S_ISREG(inode->i_mode)) { ext2_warning (sb, "ext2_file_read", "mode = %07o", inode->i_mode); return -EINVAL; } offset = filp->f_pos; size = inode->i_size; if (offset > size) left = 0; else left = size - offset; if (left > count) left = count; if (left <= 0) return 0; read = 0; block = offset >> EXT2_BLOCK_SIZE_BITS(sb); offset &= (sb->s_blocksize - 1); size = (size + sb->s_blocksize - 1) >> EXT2_BLOCK_SIZE_BITS(sb); blocks = (left + offset + sb->s_blocksize - 1) >> EXT2_BLOCK_SIZE_BITS(sb); bhb = bhe = buflist; if (filp->f_reada) { blocks += read_ahead[MAJOR(inode->i_dev)] >> (EXT2_BLOCK_SIZE_BITS(sb) - 9); if (block + blocks > size) blocks = size - block; } /* * We do this in a two stage process. We first try and request * as many blocks as we can, then we wait for the first one to * complete, and then we try and wrap up as many as are actually * done. This routine is rather generic, in that it can be used * in a filesystem by substituting the appropriate function in * for getblk * * This routine is optimized to make maximum use of the various * buffers and caches. */ do { bhrequest = 0; uptodate = 1; while (blocks) { --blocks; *bhb = ext2_getblk (inode, block++, 0, &err); if (*bhb && !(*bhb)->b_uptodate) { uptodate = 0; bhreq[bhrequest++] = *bhb; } if (++bhb == &buflist[NBUF]) bhb = buflist; /* * If the block we have on hand is uptodate, go ahead * and complete processing */ if (uptodate) break; if (bhb == bhe) break; } /* * Now request them all */ if (bhrequest) ll_rw_block (READ, bhrequest, bhreq); do { /* * Finish off all I/O that has actually completed */ if (*bhe) { wait_on_buffer (*bhe); if (!(*bhe)->b_uptodate) { /* read error? */ brelse(*bhe); if (++bhe == &buflist[NBUF]) bhe = buflist; left = 0; break; } } if (left < sb->s_blocksize - offset) chars = left; else chars = sb->s_blocksize - offset; filp->f_pos += chars; left -= chars; read += chars; if (*bhe) { memcpy_tofs (buf, offset + (*bhe)->b_data, chars); brelse (*bhe); buf += chars; } else { while (chars-- > 0) put_fs_byte (0, buf++); } offset = 0; if (++bhe == &buflist[NBUF]) bhe = buflist; } while (left > 0 && bhe != bhb && (!*bhe || !(*bhe)->b_lock)); } while (left > 0); /* * Release the read-ahead blocks */ while (bhe != bhb) { brelse (*bhe); if (++bhe == &buflist[NBUF]) bhe = buflist; } if (!read) return -EIO; filp->f_reada = 1; if (!IS_RDONLY(inode)) { inode->i_atime = CURRENT_TIME; inode->i_dirt = 1; } return read; } static int ext2_file_write (struct inode * inode, struct file * filp, char * buf, int count) { off_t pos; int written, c; struct buffer_head * bh; char * p; struct super_block * sb; int err; if (!inode) { printk("ext2_file_write: inode = NULL\n"); return -EINVAL; } sb = inode->i_sb; if (sb->s_flags & MS_RDONLY) /* * This fs has been automatically remounted ro because of errors */ return -ENOSPC; if (!S_ISREG(inode->i_mode)) { ext2_warning (sb, "ext2_file_write", "mode = %07o\n", inode->i_mode); return -EINVAL; } down(&inode->i_sem); if (filp->f_flags & O_APPEND) pos = inode->i_size; else pos = filp->f_pos; written = 0; while (written < count) { bh = ext2_getblk (inode, pos / sb->s_blocksize, 1, &err); if (!bh) { if (!written) written = err; break; } c = sb->s_blocksize - (pos % sb->s_blocksize); if (c > count-written) c = count - written; if (c != sb->s_blocksize && !bh->b_uptodate) { ll_rw_block (READ, 1, &bh); wait_on_buffer (bh); if (!bh->b_uptodate) { brelse (bh); if (!written) written = -EIO; break; } } p = (pos % sb->s_blocksize) + bh->b_data; pos += c; if (pos > inode->i_size) { inode->i_size = pos; inode->i_dirt = 1; } written += c; memcpy_fromfs (p, buf, c); buf += c; bh->b_uptodate = 1; bh->b_dirt = 1; brelse (bh); } up(&inode->i_sem); inode->i_ctime = inode->i_mtime = CURRENT_TIME; filp->f_pos = pos; inode->i_dirt = 1; return written; } /* * Called when a inode is released. Note that this is different * from ext2_open: open gets called at every open, but release * gets called only when /all/ the files are closed. */ static void ext2_release_file (struct inode * inode, struct file * filp) { if (filp->f_mode & 2) ext2_discard_prealloc (inode); } |