b1d068470b
isofs now uses an in-memory directory listing built on-the-fly instead of parsing the ISO 9660 data structures over and over for almost every request. This yields huge performance improvements. The directory listing is allocated dynamically, but Minix servers aren't normally supposed to do that because critical servers would crash if the system runs out of memory. isofs is quite frugal, won't allocate memory after having the whole directory tree cached and is not that critical (its most important job is to serve as a root file system during installation). The benefits and elegance of this scheme far outweights this small problem in practice. Change-Id: I13d070388c07d274cbee0645cbc50295c447c5b6
106 lines
2.3 KiB
C
106 lines
2.3 KiB
C
#include "inc.h"
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static char getdents_buf[GETDENTS_BUFSIZ];
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ssize_t fs_read(ino_t ino_nr, struct fsdriver_data *data, size_t bytes,
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off_t pos, int __unused call)
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{
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size_t off, chunk, block_size, cum_io;
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off_t f_size;
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struct inode *i_node;
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struct buf *bp;
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int r;
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/* Try to get inode according to its index. */
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if ((i_node = get_inode(ino_nr)) == NULL)
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return EINVAL; /* No inode found. */
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f_size = i_node->i_stat.st_size;
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if (pos >= f_size)
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return 0; /* EOF */
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/* Limit the request to the remainder of the file size. */
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if ((off_t)bytes > f_size - pos)
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bytes = (size_t)(f_size - pos);
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block_size = v_pri.logical_block_size_l;
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cum_io = 0;
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r = OK;
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/* Split the transfer into chunks that don't span two blocks. */
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while (bytes > 0) {
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off = pos % block_size;
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chunk = block_size - off;
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if (chunk > bytes)
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chunk = bytes;
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/* Read 'chunk' bytes. */
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bp = read_extent_block(&i_node->extent, pos);
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if (bp == NULL)
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panic("bp not valid in rw_chunk; this can't happen");
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r = fsdriver_copyout(data, cum_io, b_data(bp)+off, chunk);
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lmfs_put_block(bp);
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if (r != OK)
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break;
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/* Update counters and pointers. */
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bytes -= chunk; /* Bytes yet to be read. */
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cum_io += chunk; /* Bytes read so far. */
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pos += chunk; /* Position within the file. */
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}
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return (r == OK) ? cum_io : r;
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}
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ssize_t fs_getdents(ino_t ino_nr, struct fsdriver_data *data, size_t bytes,
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off_t *pos)
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{
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struct fsdriver_dentry fsdentry;
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struct inode *i_node;
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off_t cur_pos;
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int r, len;
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char *cp;
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if ((i_node = get_inode(ino_nr)) == NULL)
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return EINVAL;
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if (*pos < 0 || *pos > SSIZE_MAX)
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return EINVAL;
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r = read_directory(i_node);
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if (r != OK)
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return r;
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fsdriver_dentry_init(&fsdentry, data, bytes, getdents_buf,
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sizeof(getdents_buf));
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r = OK;
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for (cur_pos = *pos; cur_pos < i_node->dir_size; cur_pos++) {
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/* Compute the length of the name */
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cp = memchr(i_node->dir_contents[cur_pos].name, '\0', NAME_MAX);
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if (cp == NULL)
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len = NAME_MAX;
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else
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len = cp - i_node->dir_contents[cur_pos].name;
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r = fsdriver_dentry_add(&fsdentry,
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i_node->dir_contents[cur_pos].i_node->i_stat.st_ino,
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i_node->dir_contents[cur_pos].name, len,
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IFTODT(i_node->dir_contents[cur_pos].i_node->i_stat.st_mode));
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if (r <= 0)
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break;
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}
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if (r >= 0 && (r = fsdriver_dentry_finish(&fsdentry)) >= 0)
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*pos = cur_pos;
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return r;
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}
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