/* Created (MFS based): * February 2010 (Evgeniy Ivanov) */ #include "fs.h" #include #include #include #include "buf.h" #include "inode.h" #include "super.h" #include #include #include static struct buf *rahead(struct inode *rip, block_t baseblock, u64_t position, unsigned bytes_ahead); static int rw_chunk(struct inode *rip, u64_t position, unsigned off, size_t chunk, unsigned left, int call, struct fsdriver_data *data, unsigned buf_off, unsigned int block_size, int *completed); /*===========================================================================* * fs_readwrite * *===========================================================================*/ ssize_t fs_readwrite(ino_t ino_nr, struct fsdriver_data *data, size_t nrbytes, off_t position, int call) { int r; int regular; off_t f_size, bytes_left; size_t off, cum_io, block_size, chunk; mode_t mode_word; int completed; struct inode *rip; r = OK; /* Find the inode referred */ if ((rip = find_inode(fs_dev, ino_nr)) == NULL) return(EINVAL); mode_word = rip->i_mode & I_TYPE; regular = (mode_word == I_REGULAR); /* Determine blocksize */ block_size = rip->i_sp->s_block_size; f_size = rip->i_size; if (f_size < 0) f_size = MAX_FILE_POS; lmfs_reset_rdwt_err(); if (call == FSC_WRITE) { /* Check in advance to see if file will grow too big. */ if (position > (off_t) (rip->i_sp->s_max_size - nrbytes)) return(EFBIG); } cum_io = 0; /* Split the transfer into chunks that don't span two blocks. */ while (nrbytes != 0) { off = (unsigned int) (position % block_size);/* offset in blk*/ chunk = block_size - off; if (chunk > nrbytes) chunk = nrbytes; if (call == FSC_READ) { bytes_left = f_size - position; if (position >= f_size) break; /* we are beyond EOF */ if (chunk > bytes_left) chunk = (int) bytes_left; } /* Read or write 'chunk' bytes. */ r = rw_chunk(rip, ((u64_t)((unsigned long)position)), off, chunk, nrbytes, call, data, cum_io, block_size, &completed); if (r != OK) break; /* EOF reached */ if (lmfs_rdwt_err() < 0) break; /* Update counters and pointers. */ nrbytes -= chunk; /* bytes yet to be read */ cum_io += chunk; /* bytes read so far */ position += (off_t) chunk; /* position within the file */ } /* On write, update file size and access time. */ if (call == FSC_WRITE) { if (regular || mode_word == I_DIRECTORY) { if (position > f_size) rip->i_size = position; } } rip->i_seek = NO_SEEK; if (lmfs_rdwt_err() != OK) r = lmfs_rdwt_err(); /* check for disk error */ if (lmfs_rdwt_err() == END_OF_FILE) r = OK; if (r != OK) return r; if (call == FSC_READ) rip->i_update |= ATIME; if (call == FSC_WRITE) rip->i_update |= CTIME | MTIME; rip->i_dirt = IN_DIRTY; /* inode is thus now dirty */ return(cum_io); } /*===========================================================================* * rw_chunk * *===========================================================================*/ static int rw_chunk(rip, position, off, chunk, left, call, data, buf_off, block_size, completed) register struct inode *rip; /* pointer to inode for file to be rd/wr */ u64_t position; /* position within file to read or write */ unsigned off; /* off within the current block */ size_t chunk; /* number of bytes to read or write */ unsigned left; /* max number of bytes wanted after position */ int call; /* FSC_READ, FSC_WRITE, or FSC_PEEK */ struct fsdriver_data *data; /* structure for (remote) user buffer */ unsigned buf_off; /* offset in user buffer */ unsigned int block_size; /* block size of FS operating on */ int *completed; /* number of bytes copied */ { /* Read or write (part of) a block. */ register struct buf *bp = NULL; register int r = OK; int n; block_t b; dev_t dev; ino_t ino = VMC_NO_INODE; u64_t ino_off = rounddown(position, block_size); *completed = 0; if (ex64hi(position) != 0) panic("rw_chunk: position too high"); b = read_map(rip, (off_t) ex64lo(position), 0); dev = rip->i_dev; ino = rip->i_num; assert(ino != VMC_NO_INODE); if (b == NO_BLOCK) { if (call == FSC_READ) { /* Reading from a nonexistent block. Must read as all zeros.*/ r = fsdriver_zero(data, buf_off, chunk); if(r != OK) { printf("ext2fs: fsdriver_zero failed\n"); } return r; } else if (call == FSC_PEEK) { /* Peeking a nonexistent block. Report to VM. */ lmfs_zero_block_ino(dev, ino, ino_off); return OK; } else { /* Writing to a nonexistent block. * Create and enter in inode. */ if ((bp = new_block(rip, (off_t) ex64lo(position))) == NULL) return(err_code); } } else if (call != FSC_WRITE) { /* Read and read ahead if convenient. */ bp = rahead(rip, b, position, left); } else { /* Normally an existing block to be partially overwritten is first read * in. However, a full block need not be read in. If it is already in * the cache, acquire it, otherwise just acquire a free buffer. */ n = (chunk == block_size ? NO_READ : NORMAL); if (off == 0 && (off_t) ex64lo(position) >= rip->i_size) n = NO_READ; assert(ino != VMC_NO_INODE); assert(!(ino_off % block_size)); bp = lmfs_get_block_ino(dev, b, n, ino, ino_off); } /* In all cases, bp now points to a valid buffer. */ if (bp == NULL) panic("bp not valid in rw_chunk, this can't happen"); if (call == FSC_WRITE && chunk != block_size && (off_t) ex64lo(position) >= rip->i_size && off == 0) { zero_block(bp); } if (call == FSC_READ) { /* Copy a chunk from the block buffer to user space. */ r = fsdriver_copyout(data, buf_off, b_data(bp)+off, chunk); } else if (call == FSC_WRITE) { /* Copy a chunk from user space to the block buffer. */ r = fsdriver_copyin(data, buf_off, b_data(bp)+off, chunk); lmfs_markdirty(bp); } put_block(bp); return(r); } /*===========================================================================* * read_map * *===========================================================================*/ block_t read_map(rip, position, opportunistic) register struct inode *rip; /* ptr to inode to map from */ off_t position; /* position in file whose blk wanted */ int opportunistic; { /* Given an inode and a position within the corresponding file, locate the * block number in which that position is to be found and return it. */ struct buf *bp; int mindex; block_t b; unsigned long excess, block_pos; static char first_time = TRUE; static long addr_in_block; static long addr_in_block2; static long doub_ind_s; static long triple_ind_s; static long out_range_s; int iomode; iomode = opportunistic ? PEEK : NORMAL; if (first_time) { addr_in_block = rip->i_sp->s_block_size / BLOCK_ADDRESS_BYTES; addr_in_block2 = addr_in_block * addr_in_block; doub_ind_s = EXT2_NDIR_BLOCKS + addr_in_block; triple_ind_s = doub_ind_s + addr_in_block2; out_range_s = triple_ind_s + addr_in_block2 * addr_in_block; first_time = FALSE; } block_pos = position / rip->i_sp->s_block_size; /* relative blk # in file */ /* Is 'position' to be found in the inode itself? */ if (block_pos < EXT2_NDIR_BLOCKS) return(rip->i_block[block_pos]); /* It is not in the inode, so it must be single, double or triple indirect */ if (block_pos < doub_ind_s) { b = rip->i_block[EXT2_NDIR_BLOCKS]; /* address of single indirect block */ mindex = block_pos - EXT2_NDIR_BLOCKS; } else if (block_pos >= out_range_s) { /* TODO: do we need it? */ return(NO_BLOCK); } else { /* double or triple indirect block. At first if it's triple, * find double indirect block. */ excess = block_pos - doub_ind_s; b = rip->i_block[EXT2_DIND_BLOCK]; if (block_pos >= triple_ind_s) { b = rip->i_block[EXT2_TIND_BLOCK]; if (b == NO_BLOCK) return(NO_BLOCK); bp = get_block(rip->i_dev, b, NORMAL); /* get triple ind block */ ASSERT(lmfs_dev(bp) != NO_DEV); ASSERT(lmfs_dev(bp) == rip->i_dev); excess = block_pos - triple_ind_s; mindex = excess / addr_in_block2; b = rd_indir(bp, mindex); /* num of double ind block */ put_block(bp); /* release triple ind block */ excess = excess % addr_in_block2; } if (b == NO_BLOCK) return(NO_BLOCK); bp = get_block(rip->i_dev, b, iomode); /* get double indirect block */ if (bp == NULL) return NO_BLOCK; /* peeking failed */ ASSERT(lmfs_dev(bp) != NO_DEV); ASSERT(lmfs_dev(bp) == rip->i_dev); mindex = excess / addr_in_block; b = rd_indir(bp, mindex); /* num of single ind block */ put_block(bp); /* release double ind block */ mindex = excess % addr_in_block; /* index into single ind blk */ } if (b == NO_BLOCK) return(NO_BLOCK); bp = get_block(rip->i_dev, b, iomode); /* get single indirect block */ if (bp == NULL) return NO_BLOCK; /* peeking failed */ ASSERT(lmfs_dev(bp) != NO_DEV); ASSERT(lmfs_dev(bp) == rip->i_dev); b = rd_indir(bp, mindex); put_block(bp); /* release single ind block */ return(b); } struct buf *get_block_map(register struct inode *rip, u64_t position) { block_t b = read_map(rip, position, 0); /* get block number */ int block_size = get_block_size(rip->i_dev); if(b == NO_BLOCK) return NULL; position = rounddown(position, block_size); assert(rip->i_num != VMC_NO_INODE); return lmfs_get_block_ino(rip->i_dev, b, NORMAL, rip->i_num, position); } /*===========================================================================* * rd_indir * *===========================================================================*/ block_t rd_indir(bp, mindex) struct buf *bp; /* pointer to indirect block */ int mindex; /* index into *bp */ { if (bp == NULL) panic("rd_indir() on NULL"); /* TODO: use conv call */ return conv4(le_CPU, b_ind(bp)[mindex]); } /*===========================================================================* * rahead * *===========================================================================*/ static struct buf *rahead(rip, baseblock, position, bytes_ahead) register struct inode *rip; /* pointer to inode for file to be read */ block_t baseblock; /* block at current position */ u64_t position; /* position within file */ unsigned bytes_ahead; /* bytes beyond position for immediate use */ { /* Fetch a block from the cache or the device. If a physical read is * required, prefetch as many more blocks as convenient into the cache. * This usually covers bytes_ahead and is at least BLOCKS_MINIMUM. * The device driver may decide it knows better and stop reading at a * cylinder boundary (or after an error). Rw_scattered() puts an optional * flag on all reads to allow this. */ /* Minimum number of blocks to prefetch. */ # define BLOCKS_MINIMUM (nr_bufs < 50 ? 18 : 32) int nr_bufs = lmfs_nr_bufs(); int read_q_size; unsigned int blocks_ahead, fragment, block_size; block_t block, blocks_left; off_t ind1_pos; dev_t dev; struct buf *bp = NULL; static unsigned int readqsize = 0; static struct buf **read_q = NULL; u64_t position_running; if(readqsize != nr_bufs) { if(readqsize > 0) { assert(read_q != NULL); free(read_q); read_q = NULL; readqsize = 0; } assert(readqsize == 0); assert(read_q == NULL); if(!(read_q = malloc(sizeof(read_q[0])*nr_bufs))) panic("couldn't allocate read_q"); readqsize = nr_bufs; } dev = rip->i_dev; assert(dev != NO_DEV); block_size = get_block_size(dev); block = baseblock; fragment = position % block_size; position -= fragment; position_running = position; bytes_ahead += fragment; blocks_ahead = (bytes_ahead + block_size - 1) / block_size; bp = lmfs_get_block_ino(dev, block, PREFETCH, rip->i_num, position); assert(bp != NULL); if (lmfs_dev(bp) != NO_DEV) return(bp); /* The best guess for the number of blocks to prefetch: A lot. * It is impossible to tell what the device looks like, so we don't even * try to guess the geometry, but leave it to the driver. * * The floppy driver can read a full track with no rotational delay, and it * avoids reading partial tracks if it can, so handing it enough buffers to * read two tracks is perfect. (Two, because some diskette types have * an odd number of sectors per track, so a block may span tracks.) * * The disk drivers don't try to be smart. With todays disks it is * impossible to tell what the real geometry looks like, so it is best to * read as much as you can. With luck the caching on the drive allows * for a little time to start the next read. * * The current solution below is a bit of a hack, it just reads blocks from * the current file position hoping that more of the file can be found. A * better solution must look at the already available * indirect blocks (but don't call read_map!). */ blocks_left = (block_t) (rip->i_size-ex64lo(position)+(block_size-1)) / block_size; /* Go for the first indirect block if we are in its neighborhood. */ ind1_pos = (EXT2_NDIR_BLOCKS) * block_size; if ((off_t) ex64lo(position) <= ind1_pos && rip->i_size > ind1_pos) { blocks_ahead++; blocks_left++; } /* No more than the maximum request. */ if (blocks_ahead > NR_IOREQS) blocks_ahead = NR_IOREQS; /* Read at least the minimum number of blocks, but not after a seek. */ if (blocks_ahead < BLOCKS_MINIMUM && rip->i_seek == NO_SEEK) blocks_ahead = BLOCKS_MINIMUM; /* Can't go past end of file. */ if (blocks_ahead > blocks_left) blocks_ahead = blocks_left; read_q_size = 0; /* Acquire block buffers. */ for (;;) { block_t thisblock; read_q[read_q_size++] = bp; if (--blocks_ahead == 0) break; /* Don't trash the cache, leave 4 free. */ if (lmfs_bufs_in_use() >= nr_bufs - 4) break; block++; position_running += block_size; thisblock = read_map(rip, (off_t) ex64lo(position_running), 1); if (thisblock != NO_BLOCK) { bp = lmfs_get_block_ino(dev, thisblock, PREFETCH, rip->i_num, position_running); } else { bp = get_block(dev, block, PREFETCH); } if (lmfs_dev(bp) != NO_DEV) { /* Oops, block already in the cache, get out. */ put_block(bp); break; } } lmfs_rw_scattered(dev, read_q, read_q_size, READING); return(lmfs_get_block_ino(dev, baseblock, NORMAL, rip->i_num, position)); } /*===========================================================================* * get_dtype * *===========================================================================*/ static unsigned int get_dtype(struct ext2_disk_dir_desc *dp) { /* Return the type of the file identified by the given directory entry. */ if (!HAS_INCOMPAT_FEATURE(superblock, INCOMPAT_FILETYPE)) return DT_UNKNOWN; switch (dp->d_file_type) { case EXT2_FT_REG_FILE: return DT_REG; case EXT2_FT_DIR: return DT_DIR; case EXT2_FT_SYMLINK: return DT_LNK; case EXT2_FT_BLKDEV: return DT_BLK; case EXT2_FT_CHRDEV: return DT_CHR; case EXT2_FT_FIFO: return DT_FIFO; default: return DT_UNKNOWN; } } /*===========================================================================* * fs_getdents * *===========================================================================*/ ssize_t fs_getdents(ino_t ino_nr, struct fsdriver_data *data, size_t bytes, off_t *posp) { #define GETDENTS_BUFSIZE (sizeof(struct dirent) + EXT2_NAME_MAX + 1) #define GETDENTS_ENTRIES 8 static char getdents_buf[GETDENTS_BUFSIZE * GETDENTS_ENTRIES]; struct fsdriver_dentry fsdentry; struct inode *rip; int r, done; unsigned int block_size, len; off_t pos, off, block_pos, new_pos, ent_pos; struct buf *bp; struct ext2_disk_dir_desc *d_desc; ino_t child_nr; /* Check whether the position is properly aligned */ pos = *posp; if ((unsigned int) pos % DIR_ENTRY_ALIGN) return(ENOENT); if ((rip = get_inode(fs_dev, ino_nr)) == NULL) return(EINVAL); block_size = rip->i_sp->s_block_size; off = (pos % block_size); /* Offset in block */ block_pos = pos - off; done = FALSE; /* Stop processing directory blocks when done is set */ fsdriver_dentry_init(&fsdentry, data, bytes, getdents_buf, sizeof(getdents_buf)); /* The default position for the next request is EOF. If the user's buffer * fills up before EOF, new_pos will be modified. */ new_pos = rip->i_size; r = 0; for (; block_pos < rip->i_size; block_pos += block_size) { off_t temp_pos = block_pos; /* Since directories don't have holes, 'bp' cannot be NULL. */ bp = get_block_map(rip, block_pos); /* get a dir block */ assert(bp != NULL); assert(bp != NULL); /* Search a directory block. */ d_desc = (struct ext2_disk_dir_desc*) &b_data(bp); /* we need to seek to entry at off bytes. * when NEXT_DISC_DIR_POS == block_size it's last dentry. */ for (; temp_pos + conv2(le_CPU, d_desc->d_rec_len) <= pos && NEXT_DISC_DIR_POS(d_desc, &b_data(bp)) < block_size; d_desc = NEXT_DISC_DIR_DESC(d_desc)) { temp_pos += conv2(le_CPU, d_desc->d_rec_len); } for (; CUR_DISC_DIR_POS(d_desc, &b_data(bp)) < block_size; d_desc = NEXT_DISC_DIR_DESC(d_desc)) { if (d_desc->d_ino == 0) continue; /* Entry is not in use */ len = d_desc->d_name_len; assert(len <= NAME_MAX); assert(len <= EXT2_NAME_MAX); /* Need the position of this entry in the directory */ ent_pos = block_pos + ((char *)d_desc - b_data(bp)); child_nr = (ino_t) conv4(le_CPU, d_desc->d_ino); r = fsdriver_dentry_add(&fsdentry, child_nr, d_desc->d_name, len, get_dtype(d_desc)); /* If the user buffer is full, or an error occurred, stop. */ if (r <= 0) { done = TRUE; /* Record the position of this entry, it is the * starting point of the next request (unless the * position is modified with lseek). */ new_pos = ent_pos; break; } } put_block(bp); if (done) break; } if (r >= 0 && (r = fsdriver_dentry_finish(&fsdentry)) >= 0) { *posp = new_pos; rip->i_update |= ATIME; rip->i_dirt = IN_DIRTY; } put_inode(rip); /* release the inode */ return(r); }