6c46a77d95
- The lmfs_get_block*(3) API calls may now return an error. The idea is to encourage a next generation of file system services to do a better job at dealing with block read errors than the MFS-derived implementations do. These existing file systems have been changed to panic immediately upon getting a block read error, in order to let unchecked errors cause corruption. Note that libbdev already retries failing I/O operations a few times first. - The libminixfs block device I/O module (bio.c) now deals properly with end-of-file conditions on block devices. Since a device or partition size may not be a multiple of the root file system's block size, support for partial block retrival has been added, with a new internal lmfs_get_partial_block(3) call. A new test program, test85, tests the new handling of EOF conditions when reading, writing, and memory-mapping a block device. Change-Id: I05e35b6b8851488328a2679da635ebba0c6d08ce
110 lines
2.4 KiB
C
110 lines
2.4 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 = find_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 / block_size);
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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, *i_node_tmp;
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size_t cur_pos, new_pos;
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int r, len;
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char *cp;
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if ((i_node = find_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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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 = (size_t)*pos; ; cur_pos = new_pos) {
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i_node_tmp = alloc_inode();
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r = read_inode(i_node_tmp, i_node->extent, cur_pos, &new_pos);
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if ((r != OK) || (new_pos >= i_node->i_stat.st_size)) {
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put_inode(i_node_tmp);
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break;
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}
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/* Compute the length of the name */
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cp = memchr(i_node_tmp->i_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_tmp->i_name;
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r = fsdriver_dentry_add(&fsdentry, i_node_tmp->i_stat.st_ino,
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i_node_tmp->i_name, len,
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IFTODT(i_node_tmp->i_stat.st_mode));
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put_inode(i_node_tmp);
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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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