251 lines
6.4 KiB
C
251 lines
6.4 KiB
C
/*
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* linux/fs/xiafs/file.c
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*
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* Copyright (C) Q. Frank Xia, 1993.
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*
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* Based on Linus' minix/file.c
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* Copyright (C) Linus Torvalds, 1991, 1992.
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*
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* This software may be redistributed per Linux Copyright.
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*/
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#include <asm/segment.h>
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#include <asm/system.h>
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#include <linux/sched.h>
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#include <linux/fs.h>
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#include <linux/xia_fs.h>
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#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/fcntl.h>
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#include <linux/stat.h>
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#include <linux/locks.h>
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#include "xiafs_mac.h"
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#define NBUF 32
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#define MIN(a,b) (((a)<(b))?(a):(b))
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#define MAX(a,b) (((a)>(b))?(a):(b))
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static int xiafs_file_read(struct inode *, struct file *, char *, int);
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static int xiafs_file_write(struct inode *, struct file *, char *, int);
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/*
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* We have mostly NULL's here: the current defaults are ok for
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* the xiafs filesystem.
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*/
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static struct file_operations xiafs_file_operations = {
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NULL, /* lseek - default */
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xiafs_file_read, /* read */
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xiafs_file_write, /* write */
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NULL, /* readdir - bad */
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NULL, /* select - default */
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NULL, /* ioctl - default */
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generic_mmap, /* mmap */
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NULL, /* no special open is needed */
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NULL, /* release */
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xiafs_sync_file /* fsync */
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};
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struct inode_operations xiafs_file_inode_operations = {
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&xiafs_file_operations, /* default file operations */
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NULL, /* create */
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NULL, /* lookup */
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NULL, /* link */
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NULL, /* unlink */
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NULL, /* symlink */
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NULL, /* mkdir */
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NULL, /* rmdir */
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NULL, /* mknod */
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NULL, /* rename */
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NULL, /* readlink */
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NULL, /* follow_link */
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xiafs_bmap, /* bmap */
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xiafs_truncate, /* truncate */
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NULL /* permission */
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};
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static int
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xiafs_file_read(struct inode * inode, struct file * filp, char * buf, int count)
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{
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int read, left, chars;
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int zone_nr, zones, f_zones, offset;
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int bhrequest, uptodate;
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struct buffer_head ** bhb, ** bhe;
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struct buffer_head * bhreq[NBUF];
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struct buffer_head * buflist[NBUF];
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if (!inode) {
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printk("XIA-FS: inode = NULL (%s %d)\n", WHERE_ERR);
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return -EINVAL;
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}
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if (!S_ISREG(inode->i_mode)) {
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printk("XIA-FS: mode != regular (%s %d)\n", WHERE_ERR);
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return -EINVAL;
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}
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offset = filp->f_pos;
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left = inode->i_size - offset;
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if (left > count)
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left = count;
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if (left <= 0)
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return 0;
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read = 0;
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zone_nr = offset >> XIAFS_ZSIZE_BITS(inode->i_sb);
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offset &= XIAFS_ZSIZE(inode->i_sb) -1 ;
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f_zones =(inode->i_size+XIAFS_ZSIZE(inode->i_sb)-1)>>XIAFS_ZSIZE_BITS(inode->i_sb);
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zones = (left+offset+XIAFS_ZSIZE(inode->i_sb)-1) >> XIAFS_ZSIZE_BITS(inode->i_sb);
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bhb = bhe = buflist;
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if (filp->f_reada) {
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zones += read_ahead[MAJOR(inode->i_dev)] >> (1+XIAFS_ZSHIFT(inode->i_sb));
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if (zone_nr + zones > f_zones)
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zones = f_zones - zone_nr;
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}
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/* We do this in a two stage process. We first try and request
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as many blocks as we can, then we wait for the first one to
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complete, and then we try and wrap up as many as are actually
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done. This routine is rather generic, in that it can be used
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in a filesystem by substituting the appropriate function in
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for getblk.
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This routine is optimized to make maximum use of the various
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buffers and caches. */
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do {
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bhrequest = 0;
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uptodate = 1;
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while (zones--) {
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*bhb = xiafs_getblk(inode, zone_nr++, 0);
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if (*bhb && !(*bhb)->b_uptodate) {
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uptodate = 0;
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bhreq[bhrequest++] = *bhb;
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}
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if (++bhb == &buflist[NBUF])
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bhb = buflist;
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/* If the block we have on hand is uptodate, go ahead
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and complete processing. */
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if (uptodate)
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break;
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if (bhb == bhe)
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break;
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}
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/* Now request them all */
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if (bhrequest)
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ll_rw_block(READ, bhrequest, bhreq);
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do { /* Finish off all I/O that has actually completed */
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if (*bhe) {
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wait_on_buffer(*bhe);
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if (!(*bhe)->b_uptodate) { /* read error? */
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brelse(*bhe);
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if (++bhe == &buflist[NBUF])
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bhe = buflist;
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left = 0;
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break;
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}
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}
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if (left < XIAFS_ZSIZE(inode->i_sb) - offset)
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chars = left;
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else
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chars = XIAFS_ZSIZE(inode->i_sb) - offset;
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filp->f_pos += chars;
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left -= chars;
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read += chars;
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if (*bhe) {
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memcpy_tofs(buf,offset+(*bhe)->b_data,chars);
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brelse(*bhe);
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buf += chars;
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} else {
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while (chars-->0)
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put_fs_byte(0,buf++);
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}
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offset = 0;
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if (++bhe == &buflist[NBUF])
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bhe = buflist;
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} while (left > 0 && bhe != bhb && (!*bhe || !(*bhe)->b_lock));
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} while (left > 0);
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/* Release the read-ahead blocks */
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while (bhe != bhb) {
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brelse(*bhe);
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if (++bhe == &buflist[NBUF])
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bhe = buflist;
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};
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if (!read)
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return -EIO;
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filp->f_reada = 1;
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if (!IS_RDONLY (inode)) {
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inode->i_atime = CURRENT_TIME;
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inode->i_dirt = 1;
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}
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return read;
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}
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static int
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xiafs_file_write(struct inode * inode, struct file * filp, char * buf, int count)
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{
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off_t pos;
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int written, c;
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struct buffer_head * bh;
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char * cp;
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if (!inode) {
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printk("XIA-FS: inode = NULL (%s %d)\n", WHERE_ERR);
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return -EINVAL;
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}
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if (!S_ISREG(inode->i_mode)) {
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printk("XIA-FS: mode != regular (%s %d)\n", WHERE_ERR);
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return -EINVAL;
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}
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/*
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* ok, append may not work when many processes are writing at the same time
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* but so what. That way leads to madness anyway.
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*/
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if (filp->f_flags & O_APPEND)
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pos = inode->i_size;
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else
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pos = filp->f_pos;
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written = 0;
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while (written < count) {
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bh = xiafs_getblk(inode, pos >> XIAFS_ZSIZE_BITS(inode->i_sb), 1);
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if (!bh) {
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if (!written)
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written = -ENOSPC;
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break;
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}
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c = XIAFS_ZSIZE(inode->i_sb) - (pos & (XIAFS_ZSIZE(inode->i_sb) - 1));
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if (c > count-written)
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c = count-written;
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if (c != XIAFS_ZSIZE(inode->i_sb) && !bh->b_uptodate) {
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ll_rw_block(READ, 1, &bh);
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wait_on_buffer(bh);
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if (!bh->b_uptodate) {
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brelse(bh);
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if (!written)
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written = -EIO;
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break;
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}
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}
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cp = (pos & (XIAFS_ZSIZE(inode->i_sb)-1)) + bh->b_data;
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pos += c;
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if (pos > inode->i_size) {
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inode->i_size = pos;
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inode->i_dirt = 1;
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}
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written += c;
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memcpy_fromfs(cp,buf,c);
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buf += c;
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bh->b_uptodate = 1;
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bh->b_dirt = 1;
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brelse(bh);
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}
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inode->i_mtime = inode->i_ctime = CURRENT_TIME;
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filp->f_pos = pos;
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inode->i_dirt = 1;
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return written;
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}
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