/* * linux/fs/truncate.c * * (C) 1991 Linus Torvalds */ #include <errno.h> #include <linux/sched.h> #include <linux/minix_fs.h> #include <linux/tty.h> #include <linux/stat.h> #include <linux/fcntl.h> /* * Truncate has the most races in the whole filesystem: coding it is * a pain in the a**. Especially as I don't do any locking... * * The code may look a bit weird, but that's just because I've tried to * handle things like file-size changes in a somewhat graceful manner. * Anyway, truncating a file at the same time somebody else writes to it * is likely to result in pretty weird behaviour... * * The new code handles normal truncates (size = 0) as well as the more * general case (size = XXX). I hope. */ static int trunc_direct(struct inode * inode) { int i; int result = 0; #define DIRECT_BLOCK ((inode->i_size + 1023) >> 10) repeat: for (i = DIRECT_BLOCK ; i < 7 ; i++) { if (i < DIRECT_BLOCK) goto repeat; if (!inode->i_data[i]) continue; result = 1; if (minix_free_block(inode->i_dev,inode->i_data[i])) inode->i_data[i] = 0; } return result; } static int trunc_indirect(struct inode * inode, int offset, unsigned short * p) { int i; struct buffer_head * bh = NULL; unsigned short * ind; int result = 0; #define INDIRECT_BLOCK (DIRECT_BLOCK-offset) if (*p) bh = bread(inode->i_dev,*p); if (!bh) return 0; repeat: for (i = INDIRECT_BLOCK ; i < 512 ; i++) { if (i < 0) i = 0; if (i < INDIRECT_BLOCK) goto repeat; ind = i+(unsigned short *) bh->b_data; if (!*ind) continue; result = 1; if (minix_free_block(inode->i_dev,*ind)) *ind = 0; } ind = (unsigned short *) bh->b_data; for (i = 0; i < 512; i++) if (*(ind++)) break; brelse(bh); if (i >= 512) { result = 1; if (minix_free_block(inode->i_dev,*p)) *p = 0; } return result; } static int trunc_dindirect(struct inode * inode) { int i; struct buffer_head * bh = NULL; unsigned short * dind; int result = 0; #define DINDIRECT_BLOCK ((DIRECT_BLOCK-(512+7))>>9) if (inode->i_data[8]) bh = bread(inode->i_dev,inode->i_data[8]); if (!bh) return 0; repeat: for (i = DINDIRECT_BLOCK ; i < 512 ; i ++) { if (i < 0) i = 0; if (i < DINDIRECT_BLOCK) goto repeat; dind = i+(unsigned short *) bh->b_data; if (!*dind) continue; result |= trunc_indirect(inode,7+512+(i<<9),dind); } dind = (unsigned short *) bh->b_data; for (i = 0; i < 512; i++) if (*(dind++)) break; brelse(bh); if (i >= 512) { result = 1; if (minix_free_block(inode->i_dev,inode->i_data[8])) inode->i_data[8] = 0; } return result; } void minix_truncate(struct inode * inode) { int flag; if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode))) return; if (inode->i_data[7] & 0xffff0000) printk("BAD! minix inode has 16 high bits set\n"); while (1) { flag = trunc_direct(inode); flag |= trunc_indirect(inode,7,(unsigned short *)&inode->i_data[7]); flag |= trunc_dindirect(inode); if (!flag) break; current->counter = 0; schedule(); } inode->i_mtime = inode->i_ctime = CURRENT_TIME; inode->i_dirt = 1; } /* * Called when a inode is released. Note that this is different * from minix_open: open gets called at every open, but release * gets called only when /all/ the files are closed. */ void minix_release(struct inode * inode, struct file * filp) { printk("minix_release not implemented\n"); }