diff options
| -rw-r--r-- | ext2fs/truncate.c | 154 |
1 files changed, 93 insertions, 61 deletions
diff --git a/ext2fs/truncate.c b/ext2fs/truncate.c index 5d652255..cfbc5695 100644 --- a/ext2fs/truncate.c +++ b/ext2fs/truncate.c @@ -33,18 +33,46 @@ * Copyright (C) 1991, 1992 Linus Torvalds */ -/* - * 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. - */ +#include "ext2fs.h" + +#ifdef DONT_CACHE_MEMORY_OBJECTS +#define MAY_CACHE 0 +#else +#define MAY_CACHE 1 +#endif + +/* ---------------------------------------------------------------- */ + +/* Write something to each page from START to END inclusive of memory + object OBJ, but make sure the data doesns't actually change. */ +static void +poke_pages (memory_object_t obj, + vm_offset_t start, + vm_offset_t end) +{ + vm_address_t addr, poke; + vm_size_t len; + error_t err; + + while (start < end) + { + len = 8 * vm_page_size; + if (len > end - start) + len = end - start; + addr = 0; + err = vm_map (mach_task_self (), &addr, len, 0, 1, obj, start, 0, + VM_PROT_WRITE|VM_PROT_READ, VM_PROT_READ|VM_PROT_WRITE, 0); + if (!err) + { + for (poke = addr; poke < addr + len; poke += vm_page_size) + *(volatile int *)poke = *(volatile int *)poke; + vm_deallocate (mach_task_self (), addr, len); + } + start += len; + } +} + +/* ---------------------------------------------------------------- */ #define DIRECT_BLOCK(length) \ ((length + block_size - 1) / block_size) @@ -70,16 +98,13 @@ trunc_direct (struct node * node, unsigned long length) for (i = direct_block ; i < EXT2_NDIR_BLOCKS ; i++) { - block = node->dn.info.i_data[i]; + block = node->dn->info.i_data[i]; if (!block) continue; bh = bptr(block); - if (i < direct_block) - goto repeat; - - node->dn.info.i_data[i] = 0; + node->dn->info.i_data[i] = 0; node->dn_stat.st_blocks -= blocks; node->dn_stat_dirty = 1; @@ -103,6 +128,8 @@ trunc_direct (struct node * node, unsigned long length) if (free_count > 0) ext2_free_blocks (block_to_free, free_count); } + +/* ---------------------------------------------------------------- */ static void trunc_indirect (struct node * node, unsigned long length, @@ -119,12 +146,12 @@ trunc_indirect (struct node * node, unsigned long length, block = *p; if (!block) - return 0; + return; ind_bh = bptr (block); if (!ind_bh) { *p = 0; - return 0; + return; } for (i = indirect_block ; i < addr_per_block ; i++) @@ -138,11 +165,9 @@ trunc_indirect (struct node * node, unsigned long length, continue; bh = bptr (block); - if (i < indirect_block) - goto repeat; *ind = 0; - pokel_add (&node->dn.pokel, ind, sizeof *ind); + pokel_add (&node->dn->pokel, ind, sizeof *ind); if (free_count == 0) { @@ -181,9 +206,9 @@ trunc_indirect (struct node * node, unsigned long length, node->dn_stat_dirty = 1; ext2_free_blocks (block, 1); } - - return retry; } + +/* ---------------------------------------------------------------- */ static void trunc_dindirect (struct node * node, unsigned long length, @@ -197,13 +222,13 @@ trunc_dindirect (struct node * node, unsigned long length, block = *p; if (!block) - return 0; + return; dind_bh = bptr (block); if (!dind_bh) { *p = 0; - return 0; + return; } for (i = dindirect_block ; i < addr_per_block ; i++) { @@ -215,9 +240,9 @@ trunc_dindirect (struct node * node, unsigned long length, if (!block) continue; - trunc_indirect (node, offset + (i * addr_per_block), dind); + trunc_indirect (node, length, offset + (i * addr_per_block), dind); - pokel_add (&node->dn.pokel, dindh_bh, block_size); + pokel_add (&node->dn->pokel, dind_bh, block_size); } dind = (u32 *) dind_bh; @@ -233,9 +258,9 @@ trunc_dindirect (struct node * node, unsigned long length, node->dn_stat_dirty = 1; ext2_free_blocks (block, 1); } - - return retry; } + +/* ---------------------------------------------------------------- */ static void trunc_tindirect (struct node * node, unsigned long length) @@ -243,19 +268,18 @@ trunc_tindirect (struct node * node, unsigned long length) int i, block; char * tind_bh; u32 * tind, * p; - int retry = 0; int blocks = block_size / 512; int tindirect_block = TINDIRECT_BLOCK (length); - p = node->dn.info.i_data + EXT2_TIND_BLOCK; + p = node->dn->info.i_data + EXT2_TIND_BLOCK; if (!(block = *p)) - return 0; + return; tind_bh = bptr (block); if (!tind_bh) { *p = 0; - return 0; + return; } for (i = tindirect_block ; i < addr_per_block ; i++) @@ -264,12 +288,12 @@ trunc_tindirect (struct node * node, unsigned long length) i = 0; tind = i + (u32 *) tind_bh; - trunc_dindirect(node, + trunc_dindirect(node, length, (EXT2_NDIR_BLOCKS + addr_per_block + (i + 1) * addr_per_block * addr_per_block), tind); - pokel_add (&node->dn.pokel, tindh_bh, block_size); + pokel_add (&node->dn->pokel, tind_bh, block_size); } tind = (u32 *) tind_bh; @@ -296,8 +320,10 @@ trunc_tindirect (struct node * node, unsigned long length) static void force_delayed_copies (struct node *node, off_t length) { + struct user_pager_info *upi; + spin_lock (&node_to_page_lock); - upi = np->dn->fileinfo; + upi = node->dn->fileinfo; if (upi) pager_reference (upi->p); spin_unlock (&node_to_page_lock); @@ -307,10 +333,10 @@ force_delayed_copies (struct node *node, off_t length) mach_port_t obj; pager_change_attributes (upi->p, MAY_CACHE, MEMORY_OBJECT_COPY_NONE, 1); - obj = diskfs_get_filemap (np); - poke_pages (obj, round_page (length), round_page (np->allocsize)); + obj = diskfs_get_filemap (node); + poke_pages (obj, round_page (length), round_page (node->allocsize)); mach_port_deallocate (mach_task_self (), obj); - pager_flush_some (upi->p, round_page(length), np->allocsize - length, 1); + pager_flush_some (upi->p, round_page(length), node->allocsize - length, 1); pager_unreference (upi->p); } } @@ -318,10 +344,13 @@ force_delayed_copies (struct node *node, off_t length) static void enable_delayed_copies (struct node *node) { + struct user_pager_info *upi; + spin_lock (&node_to_page_lock); - upi = np->dn->fileinfo; + upi = node->dn->fileinfo; if (upi) pager_reference (upi->p); + spin_unlock (&node_to_page_lock); if (upi) { @@ -332,16 +361,17 @@ enable_delayed_copies (struct node *node) /* ---------------------------------------------------------------- */ -/* The user must define this function. Truncate locked node NP to be SIZE - bytes long. (If NP is already less than or equal to SIZE bytes +/* The user must define this function. Truncate locked node NODE to be SIZE + bytes long. (If NODE is already less than or equal to SIZE bytes long, do nothing.) If this is a symlink (and diskfs_shortcut_symlink is set) then this should clear the symlink, even if diskfs_create_symlink_hook stores the link target elsewhere. */ error_t -diskfs_truncate (struct node *np, off_t length) +diskfs_truncate (struct node *node, off_t length) { + error_t err; int offset; - mode_t mode = node->dn_state.st_mode; + mode_t mode = node->dn_stat.st_mode; if (S_ISDIR(mode)) return EISDIR; @@ -350,7 +380,7 @@ diskfs_truncate (struct node *np, off_t length) if (IS_APPEND(node) || IS_IMMUTABLE(node)) return EINVAL; - if (length >= np->dn_stat.st_size) + if (length >= node->dn_stat.st_size) return 0; assert (!diskfs_readonly); @@ -364,33 +394,33 @@ diskfs_truncate (struct node *np, off_t length) offset = length % block_size; if (offset > 0) { - diskfs_node_rdwr (np, (void *)zeroblock, length, block_size - offset, + diskfs_node_rdwr (node, (void *)zeroblock, length, block_size - offset, 1, 0, 0); - diskfs_file_update (np, 1); + diskfs_file_update (node, 1); } ext2_discard_prealloc(node); - force_delayed_copies (np, length); + force_delayed_copies (node, length); - rwlock_writer_lock (&np->dn->alloc_lock); + rwlock_writer_lock (&node->dn->alloc_lock); /* Update the size on disk; fsck will finish freeing blocks if necessary should we crash. */ - np->dn_stat.st_size = length; - np->dn_set_mtime = 1; - np->dn_set_ctime = 1; - diskfs_node_update (np, 1); + node->dn_stat.st_size = length; + node->dn_set_mtime = 1; + node->dn_set_ctime = 1; + diskfs_node_update (node, 1); err = diskfs_catch_exception(); if (!err) { trunc_direct(node, length); trunc_indirect (node, length, EXT2_IND_BLOCK, - (u32 *) &node->dn.info.i_data[EXT2_IND_BLOCK]); + (u32 *) &node->dn->info.i_data[EXT2_IND_BLOCK]); trunc_dindirect (node, length, EXT2_IND_BLOCK + EXT2_ADDR_PER_BLOCK(sblock), - (u32 *) &node->dn.info.i_data[EXT2_DIND_BLOCK]); + (u32 *) &node->dn->info.i_data[EXT2_DIND_BLOCK]); trunc_tindirect (node, length); } @@ -399,17 +429,19 @@ diskfs_truncate (struct node *np, off_t length) node->dn_stat_dirty = 1; /* Now we can permit delayed copies again. */ - enable_delayed_copies (np); + enable_delayed_copies (node); + + return 0; } /* The user must define this function. Grow the disk allocated to locked node - NP to be at least SIZE bytes, and set NP->allocsize to the actual + NODE to be at least SIZE bytes, and set NODE->allocsize to the actual allocated size. (If the allocated size is already SIZE bytes, do nothing.) CRED identifies the user responsible for the call. */ error_t -diskfs_grow (struct node *np, off_t size, struct protid *cred) +diskfs_grow (struct node *node, off_t size, struct protid *cred) { - if (size > np->allocsize) - np->allocsize = size; + if (size > node->allocsize) + node->allocsize = size; return 0; } |