EXT2 file system inode.c with my comments

/* *  linux/fs/ext2/inode.c * * Copyright (C) 1992, 1993, 1994, 1995 * Remy Card ([e-mail]) * Laboratoire MASI - Institut Blaise Pascal * Universite Pierre et Marie Curie (Paris VI) * *  from * *  linux/fs/minix/inode.c * *  Copyright (C) 1991, 1992  Linus Torvalds * *  Goal-directed block allocation by Stephen Tweedie * ([e-mail]), 1993, 1998 *  Big-endian to little-endian byte-swapping/bitmaps by *        David S. Miller ([e-mail]), 1995 *  64-bit file support on 64-bit platforms by Jakub Jelinek * ([e-mail]) * *  Assorted race fixes, rewrite of ext2_get_block() by Al Viro, 2000 */#include <linux/time.h>#include <linux/highuid.h>#include <linux/pagemap.h>#include <linux/quotaops.h>#include <linux/module.h>#include <linux/writeback.h>#include <linux/buffer_head.h>#include <linux/mpage.h>#include <linux/fiemap.h>#include <linux/namei.h>#include "ext2.h"#include "acl.h"#include "xip.h"MODULE_AUTHOR("Remy Card and others");MODULE_DESCRIPTION("Second Extended Filesystem");MODULE_LICENSE("GPL");static int __ext2_write_inode(struct inode *inode, int do_sync);/* * Test whether an inode is a fast symlink. */static inline int ext2_inode_is_fast_symlink(struct inode *inode){int ea_blocks = EXT2_I(inode)->i_file_acl ?(inode->i_sb->s_blocksize >> 9) : 0;return (S_ISLNK(inode->i_mode) &&inode->i_blocks - ea_blocks == 0);}static void ext2_truncate_blocks(struct inode *inode, loff_t offset);static void ext2_write_failed(struct address_space *mapping, loff_t to){struct inode *inode = mapping->host;if (to > inode->i_size) {/*i guess here clean the page cache from size to to*/truncate_pagecache(inode, to, inode->i_size);ext2_truncate_blocks(inode, inode->i_size);}}/* * Called at the last iput() if i_nlink is zero. evict it from pagecache */void ext2_evict_inode(struct inode * inode){struct ext2_block_alloc_info *rsv;int want_delete = 0;if (!inode->i_nlink && !is_bad_inode(inode)) {want_delete = 1;/*no link and regular inode*/dquot_initialize(inode);} else {dquot_drop(inode);}/*clean all the i_data page cache fo the inode*/truncate_inode_pages(&inode->i_data, 0);if (want_delete) {/* set dtime */EXT2_I(inode)->i_dtime= get_seconds();/*mark the cache dirty to be evicted*/mark_inode_dirty(inode);/*sync inode data to page cache*/__ext2_write_inode(inode, inode_needs_sync(inode));/* truncate to 0 */inode->i_size = 0;/*i_block is the block number of inode*/if (inode->i_blocks)ext2_truncate_blocks(inode, 0);}/*invalidate the buffer data of the inode, and write back all data*/invalidate_inode_buffers(inode);end_writeback(inode);/*discard the reservation window of the inode, so rb tree evict them*/ext2_discard_reservation(inode);rsv = EXT2_I(inode)->i_block_alloc_info;EXT2_I(inode)->i_block_alloc_info = NULL;if (unlikely(rsv))/*free the space, clean the pointer*/kfree(rsv);if (want_delete)/*at last, free the inode*/ext2_free_inode(inode);}typedef struct {__le32*p;__le32key;struct buffer_head *bh;} Indirect;static inline void add_chain(Indirect *p, struct buffer_head *bh, __le32 *v){p->key = *(p->p = v);p->bh = bh;}static inline int verify_chain(Indirect *from, Indirect *to){while (from <= to && from->key == *from->p)from++;return (from > to);}/** *ext2_block_to_path - parse the block number into array of offsets *@inode: inode in question (we are only interested in its superblock) *@i_block: block number to be parsed *@offsets: array to store the offsets in *      @boundary: set this non-zero if the referred-to block is likely to be *             followed (on disk) by an indirect block. *To store the locations of file's data ext2 uses a data structure common *for UNIX filesystems - tree of pointers anchored in the inode, with *data blocks at leaves and indirect blocks in intermediate nodes. *This function translates the block number into path in that tree - *return value is the path length and @offsets[n] is the offset of *pointer to (n+1)th node in the nth one. If @block is out of range *(negative or too large) warning is printed and zero returned. * *Note: function doesn't find node addresses, so no IO is needed. All *we need to know is the capacity of indirect blocks (taken from the *inode->i_sb). *//* * Portability note: the last comparison (check that we fit into triple * indirect block) is spelled differently, because otherwise on an * architecture with 32-bit longs and 8Kb pages we might get into trouble * if our filesystem had 8Kb blocks. We might use long long, but that would * kill us on x86. Oh, well, at least the sign propagation does not matter - * i_block would have to be negative in the very beginning, so we would not * get there at all. */static int ext2_block_to_path(struct inode *inode,long i_block, int offsets[4], int *boundary){int ptrs = EXT2_ADDR_PER_BLOCK(inode->i_sb); /*the number address data can be put in one block*/int ptrs_bits = EXT2_ADDR_PER_BLOCK_BITS(inode->i_sb);const long direct_blocks = EXT2_NDIR_BLOCKS, indirect_blocks = ptrs, /*that's why indirect block numbers is ptrs*/double_blocks = (1 << (ptrs_bits * 2)); /*shifting, so that double can know*/int n = 0;int final = 0;if (i_block < 0) { /*maybe, no data or error*/ext2_msg(inode->i_sb, KERN_WARNING,"warning: %s: block < 0", __func__);} else if (i_block < direct_blocks) { /*the block numbers <13*/offsets[n++] = i_block; /*level 1 ending offsets[1]*/final = direct_blocks; /*final is the direct endy*/} else if ( (i_block -= direct_blocks) < indirect_blocks) {offsets[n++] = EXT2_IND_BLOCK; /*level 1 number ==13*/offsets[n++] = i_block; /*level 2 numbers ==i_blocks-direct_blocks*/final = ptrs; /*final is the indirect ending*/} else if ((i_block -= indirect_blocks) < double_blocks) {offsets[n++] = EXT2_DIND_BLOCK;offsets[n++] = i_block >> ptrs_bits;offsets[n++] = i_block & (ptrs - 1);final = ptrs;} else if (((i_block -= double_blocks) >> (ptrs_bits * 2)) < ptrs) {offsets[n++] = EXT2_TIND_BLOCK;offsets[n++] = i_block >> (ptrs_bits * 2);offsets[n++] = (i_block >> ptrs_bits) & (ptrs - 1);offsets[n++] = i_block & (ptrs - 1);final = ptrs;} else { /*file size is larger than the address constrain*/ext2_msg(inode->i_sb, KERN_WARNING,"warning: %s: block is too big", __func__);}if (boundary)*boundary = final - 1 - (i_block & (ptrs - 1));/*only in indirect case, it is the offsets*/return n;/*return which level it referenced*/}/** *ext2_get_branch - read the chain of indirect blocks leading to data *@inode: inode in question *@depth: depth of the chain (1 - direct pointer, etc.) *@offsets: offsets of pointers in inode/indirect blocks *@chain: place to store the result *@err: here we store the error value * *Function fills the array of triples <key, p, bh> and returns %NULL *if everything went OK or the pointer to the last filled triple *(incomplete one) otherwise. Upon the return chain[i].key contains *the number of (i+1)-th block in the chain (as it is stored in memory, *i.e. little-endian 32-bit), chain[i].p contains the address of that *number (it points into struct inode for i==0 and into the bh->b_data *for i>0) and chain[i].bh points to the buffer_head of i-th indirect *block for i>0 and NULL for i==0. In other words, it holds the block *numbers of the chain, addresses they were taken from (and where we can *verify that chain did not change) and buffer_heads hosting these *numbers. * *Function stops when it stumbles upon zero pointer (absent block) *(pointer to last triple returned, *@err == 0) *or when it gets an IO error reading an indirect block *(ditto, *@err == -EIO) *or when it notices that chain had been changed while it was reading *(ditto, *@err == -EAGAIN) *or when it reads all @depth-1 indirect blocks successfully and finds *the whole chain, all way to the data (returns %NULL, *err == 0). */static Indirect *ext2_get_branch(struct inode *inode, int depth, int *offsets, Indirect chain[4], int *err){struct super_block *sb = inode->i_sb;Indirect *p = chain; /*to the chain head*/struct buffer_head *bh;*err = 0;/* i_data is not going away, no lock needed *//*file data start address+offset which is the data start we need, add to the chain*/add_chain (chain, NULL, EXT2_I(inode)->i_data + *offsets);if (!p->key)goto no_block;while (--depth) {bh = sb_bread(sb, le32_to_cpu(p->key));if (!bh)goto failure;read_lock(&EXT2_I(inode)->i_meta_lock); /*lock the metadata read*/if (!verify_chain(chain, p)) /*if the it is changed, fail*/goto changed;/*if no change, do it again, all plus 1*/add_chain(++p, bh, (__le32*)bh->b_data + *++offsets);read_unlock(&EXT2_I(inode)->i_meta_lock);if (!p->key)goto no_block;}return NULL;changed:read_unlock(&EXT2_I(inode)->i_meta_lock);brelse(bh);*err = -EAGAIN;goto no_block;failure:*err = -EIO;no_block:return p;}/** *ext2_find_near - find a place for allocation with sufficient locality *@inode: owner *@ind: descriptor of indirect block. * *This function returns the preferred place for block allocation. *It is used when heuristic for sequential allocation fails. *Rules are: *  + if there is a block to the left of our position - allocate near it. *  + if pointer will live in indirect block - allocate near that block. *  + if pointer will live in inode - allocate in the same cylinder group. * * In the latter case we colour the starting block by the callers PID to * prevent it from clashing with concurrent allocations for a different inode * in the same block group.   The PID is used here so that functionally related * files will be close-by on-disk. * *Caller must make sure that @ind is valid and will stay that way. */static ext2_fsblk_t ext2_find_near(struct inode *inode, Indirect *ind){struct ext2_inode_info *ei = EXT2_I(inode);__le32 *start = ind->bh ? (__le32 *) ind->bh->b_data : ei->i_data;__le32 *p;ext2_fsblk_t bg_start;ext2_fsblk_t colour;/* Try to find previous block */for (p = ind->p - 1; p >= start; p--)/*go through the chain one by one*/if (*p)return le32_to_cpu(*p);/* No such thing, so let's try location of indirect block */if (ind->bh)return ind->bh->b_blocknr;/* * It is going to be referred from inode itself? OK, just put it into * the same cylinder group then. */bg_start = ext2_group_first_block_no(inode->i_sb, ei->i_block_group);colour = (current->pid % 16) *(EXT2_BLOCKS_PER_GROUP(inode->i_sb) / 16); /*must be one of the block in this group*/return bg_start + colour;}/** *ext2_find_goal - find a preferred place for allocation. *@inode: owner *@block:  block we want *@partial: pointer to the last triple within a chain * *Returns preferred place for a block (the goal). */static inline ext2_fsblk_t ext2_find_goal(struct inode *inode, long block,  Indirect *partial){struct ext2_block_alloc_info *block_i;block_i = EXT2_I(inode)->i_block_alloc_info;/* * try the heuristic for sequential allocation, * failing that at least try to get decent locality. */if (block_i && (block == block_i->last_alloc_logical_block + 1)&& (block_i->last_alloc_physical_block != 0)) {return block_i->last_alloc_physical_block + 1;}return ext2_find_near(inode, partial);}/** *ext2_blks_to_allocate: Look up the block map and count the number *of direct blocks need to be allocated for the given branch. * * @branch: chain of indirect blocks *@k: number of blocks need for indirect blocks *@blks: number of data blocks to be mapped. *@blocks_to_boundary:  the offset in the indirect block * *return the total number of blocks to be allocate, including the *direct and indirect blocks. */static intext2_blks_to_allocate(Indirect * branch, int k, unsigned long blks,int blocks_to_boundary){unsigned long count = 0;/* * Simple case, [t,d]Indirect block(s) has not allocated yet * then it's clear blocks on that path have not allocated */if (k > 0) {/* right now don't hanel cross boundary allocation */if (blks < blocks_to_boundary + 1)count += blks; /*now, count is the blks*/elsecount += blocks_to_boundary + 1; /*now, count is the boundary+1*/return count;}count++;while (count < blks && count <= blocks_to_boundary&& le32_to_cpu(*(branch[0].p + count)) == 0) {/*allocate 1 direct block, or direct blocks less than boundary*/count++;}return count;}/** *ext2_alloc_blocks: multiple allocate blocks needed for a branch *@indirect_blks: the number of blocks need to allocate for indirect *blocks * *@new_blocks: on return it will store the new block numbers for *the indirect blocks(if needed) and the first direct block, *@blks:on return it will store the total number of allocated *direct blocks */static int ext2_alloc_blocks(struct inode *inode,ext2_fsblk_t goal, int indirect_blks, int blks,ext2_fsblk_t new_blocks[4], int *err){int target, i;unsigned long count = 0;int index = 0;ext2_fsblk_t current_block = 0;int ret = 0;/* * Here we try to allocate the requested multiple blocks at once, * on a best-effort basis. * To build a branch, we should allocate blocks for * the indirect blocks(if not allocated yet), and at least * the first direct block of this branch.  That's the * minimum number of blocks need to allocate(required) */target = blks + indirect_blks; /*the total si direct + indirect*/while (1) {count = target;/* allocating blocks for indirect blocks and direct blocks, current_block* is the fs range block address that allocated, and the length is *count<=target */current_block = ext2_new_blocks(inode,goal,&count,err);if (*err)goto failed_out;target -= count;  /*reduce the waiting value to be allocated*//* allocate blocks for indirect blocks */while (index < indirect_blks && count) {new_blocks[index++] = current_block++;count--;}if (count > 0)/*it is only possible, index>=indirect blocks and allocated*/break;}/* save the new block number for the first direct block */new_blocks[index] = current_block;/* total number of blocks allocated for direct blocks */ret = count;*err = 0;return ret;failed_out:for (i = 0; i <index; i++)ext2_free_blocks(inode, new_blocks[i], 1);/*release those blocks*/if (index)mark_inode_dirty(inode);return ret;}/** *ext2_alloc_branch - allocate and set up a chain of blocks. *@inode: owner *@num: depth of the chain (number of blocks to allocate) *@offsets: offsets (in the blocks) to store the pointers to next. *@branch: place to store the chain in. * *This function allocates @num blocks, zeroes out all but the last one, *links them into chain and (if we are synchronous) writes them to disk. *In other words, it prepares a branch that can be spliced onto the *inode. It stores the information about that chain in the branch[], in *the same format as ext2_get_branch() would do. We are calling it after *we had read the existing part of chain and partial points to the last *triple of that (one with zero ->key). Upon the exit we have the same *picture as after the successful ext2_get_block(), except that in one *place chain is disconnected - *branch->p is still zero (we did not *set the last link), but branch->key contains the number that should *be placed into *branch->p to fill that gap. * *If allocation fails we free all blocks we've allocated (and forget *their buffer_heads) and return the error value the from failed *ext2_alloc_block() (normally -ENOSPC). Otherwise we set the chain *as described above and return 0. */static int ext2_alloc_branch(struct inode *inode,int indirect_blks, int *blks, ext2_fsblk_t goal,int *offsets, Indirect *branch){int blocksize = inode->i_sb->s_blocksize;int i, n = 0;int err = 0;struct buffer_head *bh;int num;ext2_fsblk_t new_blocks[4];ext2_fsblk_t current_block;num = ext2_alloc_blocks(inode, goal, indirect_blks,*blks, new_blocks, &err);if (err)return err;branch[0].key = cpu_to_le32(new_blocks[0]);/* * metadata blocks and data blocks are allocated. */for (n = 1; n <= indirect_blks;  n++) {/* * Get buffer_head for parent block, zero it out * and set the pointer to new one, then send * parent to disk. */bh = sb_getblk(inode->i_sb, new_blocks[n-1]);branch[n].bh = bh; /*start from the current_block address*/lock_buffer(bh);/*lock it*/memset(bh->b_data, 0, blocksize);branch[n].p = (__le32 *) bh->b_data + offsets[n];branch[n].key = cpu_to_le32(new_blocks[n]);*branch[n].p = branch[n].key;/*why?*/if ( n == indirect_blks) {current_block = new_blocks[n];/* * End of chain, update the last new metablock of * the chain to point to the new allocated * data blocks numbers */for (i=1; i < num; i++)*(branch[n].p + i) = cpu_to_le32(++current_block);}set_buffer_uptodate(bh);unlock_buffer(bh);mark_buffer_dirty_inode(bh, inode);/* We used to sync bh here if IS_SYNC(inode). * But we now rely upon generic_write_sync() * and b_inode_buffers.  But not for directories. */if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode))sync_dirty_buffer(bh);}*blks = num;return err;}/** * ext2_splice_branch - splice the allocated branch onto inode. * @inode: owner * @block: (logical) number of block we are adding * @where: location of missing link * @num:   number of indirect blocks we are adding * @blks:  number of direct blocks we are adding * * This function fills the missing link and does all housekeeping needed in * inode (->i_blocks, etc.). In case of success we end up with the full * chain to new block and return 0. */static void ext2_splice_branch(struct inode *inode,long block, Indirect *where, int num, int blks){int i;struct ext2_block_alloc_info *block_i;ext2_fsblk_t current_block;block_i = EXT2_I(inode)->i_block_alloc_info;/* XXX LOCKING probably should have i_meta_lock ?*//* That's it */*where->p = where->key;/**p point to the block number?*//* * Update the host buffer_head or inode to point to more just allocated * direct blocks blocks */if (num == 0 && blks > 1) { /*direct blocks is more than 1*/current_block = le32_to_cpu(where->key) + 1;/*the branch start+1?*/for (i = 1; i < blks; i++)*(where->p + i ) = cpu_to_le32(current_block++); /*fill*/}/* * update the most recently allocated logical & physical block * in i_block_alloc_info, to assist find the proper goal block for next * allocation */if (block_i) {block_i->last_alloc_logical_block = block + blks - 1;block_i->last_alloc_physical_block =le32_to_cpu(where[num].key) + blks - 1;}/* We are done with atomic stuff, now do the rest of housekeeping *//* had we spliced it onto indirect block? */if (where->bh)mark_buffer_dirty_inode(where->bh, inode);inode->i_ctime = CURRENT_TIME_SEC;mark_inode_dirty(inode);}/* * Allocation strategy is simple: if we have to allocate something, we will * have to go the whole way to leaf. So let's do it before attaching anything * to tree, set linkage between the newborn blocks, write them if sync is * required, recheck the path, free and repeat if check fails, otherwise * set the last missing link (that will protect us from any truncate-generated * removals - all blocks on the path are immune now) and possibly force the * write on the parent block. * That has a nice additional property: no special recovery from the failed * allocations is needed - we simply release blocks and do not touch anything * reachable from inode. * * `handle' can be NULL if create == 0. * * return > 0, # of blocks mapped or allocated. * return = 0, if plain lookup failed. * return < 0, error case. */static int ext2_get_blocks(struct inode *inode,   sector_t iblock, unsigned long maxblocks,   struct buffer_head *bh_result,   int create){int err = -EIO;int offsets[4];Indirect chain[4];Indirect *partial;ext2_fsblk_t goal;int indirect_blks;int blocks_to_boundary = 0;int depth;struct ext2_inode_info *ei = EXT2_I(inode);int count = 0;ext2_fsblk_t first_block = 0;BUG_ON(maxblocks == 0);/*get the depth, the offset array and blocks to boundary*/depth = ext2_block_to_path(inode,iblock,offsets,&blocks_to_boundary);if (depth == 0)return (err);partial = ext2_get_branch(inode, depth, offsets, chain, &err);/* Simplest case - block found, no allocation needed */if (!partial) {first_block = le32_to_cpu(chain[depth - 1].key);clear_buffer_new(bh_result); /* What's this do? */count++;/*map more blocks*/while (count < maxblocks && count <= blocks_to_boundary) {ext2_fsblk_t blk;if (!verify_chain(chain, chain + depth - 1)) {/* * Indirect block might be removed by * truncate while we were reading it. * Handling of that case: forget what we've * got now, go to reread. */err = -EAGAIN;count = 0;break;}blk = le32_to_cpu(*(chain[depth-1].p + count));if (blk == first_block + count)count++;elsebreak;}if (err != -EAGAIN)goto got_it;}/* Next simple case - plain lookup or failed read of indirect block */if (!create || err == -EIO)goto cleanup;mutex_lock(&ei->truncate_mutex);/* * If the indirect block is missing while we are reading * the chain(ext2_get_branch() returns -EAGAIN err), or * if the chain has been changed after we grab the semaphore, * (either because another process truncated this branch, or * another get_block allocated this branch) re-grab the chain to see if * the request block has been allocated or not. * * Since we already block the truncate/other get_block * at this point, we will have the current copy of the chain when we * splice the branch into the tree. */if (err == -EAGAIN || !verify_chain(chain, partial)) {while (partial > chain) {brelse(partial->bh);partial--;}partial = ext2_get_branch(inode, depth, offsets, chain, &err);if (!partial) {count++;mutex_unlock(&ei->truncate_mutex);if (err)goto cleanup;clear_buffer_new(bh_result);goto got_it;}}/* * Okay, we need to do block allocation.  Lazily initialize the block * allocation info here if necessary*/if (S_ISREG(inode->i_mode) && (!ei->i_block_alloc_info))ext2_init_block_alloc_info(inode);goal = ext2_find_goal(inode, iblock, partial);/* the number of blocks need to allocate for [d,t]indirect blocks */indirect_blks = (chain + depth) - partial - 1;/* * Next look up the indirect map to count the totoal number of * direct blocks to allocate for this branch. */count = ext2_blks_to_allocate(partial, indirect_blks,maxblocks, blocks_to_boundary);/* * XXX ???? Block out ext2_truncate while we alter the tree */err = ext2_alloc_branch(inode, indirect_blks, &count, goal,offsets + (partial - chain), partial);if (err) {mutex_unlock(&ei->truncate_mutex);goto cleanup;}if (ext2_use_xip(inode->i_sb)) {/* * we need to clear the block */err = ext2_clear_xip_target (inode,le32_to_cpu(chain[depth-1].key));if (err) {mutex_unlock(&ei->truncate_mutex);goto cleanup;}}ext2_splice_branch(inode, iblock, partial, indirect_blks, count);mutex_unlock(&ei->truncate_mutex);set_buffer_new(bh_result);got_it:map_bh(bh_result, inode->i_sb, le32_to_cpu(chain[depth-1].key));if (count > blocks_to_boundary)set_buffer_boundary(bh_result);err = count;/* Clean up and exit */partial = chain + depth - 1;/* the whole chain */cleanup:while (partial > chain) {brelse(partial->bh);partial--;}return err;}/*for now, give up understanding, do it next time, it is important*/int ext2_get_block(struct inode *inode, sector_t iblock, struct buffer_head *bh_result, int create){unsigned max_blocks = bh_result->b_size >> inode->i_blkbits;/*allocate the blocks and return the allocated numbers*/int ret = ext2_get_blocks(inode, iblock, max_blocks,      bh_result, create);if (ret > 0) {bh_result->b_size = (ret << inode->i_blkbits);/*block size in bits?*/ret = 0;}return ret;}int ext2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,u64 start, u64 len){return generic_block_fiemap(inode, fieinfo, start, len,    ext2_get_block);}static int ext2_writepage(struct page *page, struct writeback_control *wbc){return block_write_full_page(page, ext2_get_block, wbc);/*call back function*/}static int ext2_readpage(struct file *file, struct page *page){return mpage_readpage(page, ext2_get_block);}static intext2_readpages(struct file *file, struct address_space *mapping,struct list_head *pages, unsigned nr_pages){return mpage_readpages(mapping, pages, nr_pages, ext2_get_block);}static intext2_write_begin(struct file *file, struct address_space *mapping,loff_t pos, unsigned len, unsigned flags,struct page **pagep, void **fsdata){int ret;ret = block_write_begin(mapping, pos, len, flags, pagep,ext2_get_block);if (ret < 0)ext2_write_failed(mapping, pos + len);return ret;}static int ext2_write_end(struct file *file, struct address_space *mapping,loff_t pos, unsigned len, unsigned copied,struct page *page, void *fsdata){int ret;ret = generic_write_end(file, mapping, pos, len, copied, page, fsdata);if (ret < len)ext2_write_failed(mapping, pos + len);return ret;}static intext2_nobh_write_begin(struct file *file, struct address_space *mapping,loff_t pos, unsigned len, unsigned flags,struct page **pagep, void **fsdata){int ret;ret = nobh_write_begin(mapping, pos, len, flags, pagep, fsdata,       ext2_get_block);if (ret < 0)ext2_write_failed(mapping, pos + len);return ret;}static int ext2_nobh_writepage(struct page *page,struct writeback_control *wbc){return nobh_writepage(page, ext2_get_block, wbc);}static sector_t ext2_bmap(struct address_space *mapping, sector_t block){return generic_block_bmap(mapping,block,ext2_get_block);}static ssize_text2_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,loff_t offset, unsigned long nr_segs){struct file *file = iocb->ki_filp;struct address_space *mapping = file->f_mapping;struct inode *inode = mapping->host;ssize_t ret;ret = blockdev_direct_IO(rw, iocb, inode, iov, offset, nr_segs, ext2_get_block);if (ret < 0 && (rw & WRITE))ext2_write_failed(mapping, offset + iov_length(iov, nr_segs));return ret;}static intext2_writepages(struct address_space *mapping, struct writeback_control *wbc){return mpage_writepages(mapping, wbc, ext2_get_block);}const struct address_space_operations ext2_aops = {.readpage= ext2_readpage,.readpages= ext2_readpages,.writepage= ext2_writepage,.write_begin= ext2_write_begin,.write_end= ext2_write_end,.bmap= ext2_bmap,.direct_IO= ext2_direct_IO,.writepages= ext2_writepages,.migratepage= buffer_migrate_page,.is_partially_uptodate= block_is_partially_uptodate,.error_remove_page= generic_error_remove_page,};const struct address_space_operations ext2_aops_xip = {.bmap= ext2_bmap,.get_xip_mem= ext2_get_xip_mem,};const struct address_space_operations ext2_nobh_aops = {.readpage= ext2_readpage,.readpages= ext2_readpages,.writepage= ext2_nobh_writepage,.write_begin= ext2_nobh_write_begin,.write_end= nobh_write_end,.bmap= ext2_bmap,.direct_IO= ext2_direct_IO,.writepages= ext2_writepages,.migratepage= buffer_migrate_page,.error_remove_page= generic_error_remove_page,};/* * Probably it should be a library function... search for first non-zero word * or memcmp with zero_page, whatever is better for particular architecture. * Linus? */static inline int all_zeroes(__le32 *p, __le32 *q){while (p < q)if (*p++)return 0;return 1;}/** *ext2_find_shared - find the indirect blocks for partial truncation. *@inode:  inode in question *@depth:  depth of the affected branch *@offsets: offsets of pointers in that branch (see ext2_block_to_path) *@chain:  place to store the pointers to partial indirect blocks *@top:  place to the (detached) top of branch * *This is a helper function used by ext2_truncate(). * *When we do truncate() we may have to clean the ends of several indirect *blocks but leave the blocks themselves alive. Block is partially *truncated if some data below the new i_size is referred from it (and *it is on the path to the first completely truncated data block, indeed). *We have to free the top of that path along with everything to the right *of the path. Since no allocation past the truncation point is possible *until ext2_truncate() finishes, we may safely do the latter, but top *of branch may require special attention - pageout below the truncation *point might try to populate it. * *We atomically detach the top of branch from the tree, store the block *number of its root in *@top, pointers to buffer_heads of partially *truncated blocks - in @chain[].bh and pointers to their last elements *that should not be removed - in @chain[].p. Return value is the pointer *to last filled element of @chain. * *The work left to caller to do the actual freeing of subtrees: *a) free the subtree starting from *@top *b) free the subtrees whose roots are stored in *(@chain[i].p+1 .. end of @chain[i].bh->b_data) *c) free the subtrees growing from the inode past the @chain[0].p *(no partially truncated stuff there). */static Indirect *ext2_find_shared(struct inode *inode,int depth,int offsets[4],Indirect chain[4],__le32 *top){Indirect *partial, *p;int k, err;*top = 0;for (k = depth; k > 1 && !offsets[k-1]; k--);partial = ext2_get_branch(inode, k, offsets, chain, &err);if (!partial)partial = chain + k-1;/* * If the branch acquired continuation since we've looked at it - * fine, it should all survive and (new) top doesn't belong to us. */write_lock(&EXT2_I(inode)->i_meta_lock);if (!partial->key && *partial->p) {write_unlock(&EXT2_I(inode)->i_meta_lock);goto no_top;}for (p=partial; p>chain && all_zeroes((__le32*)p->bh->b_data,p->p); p--);/* * OK, we've found the last block that must survive. The rest of our * branch should be detached before unlocking. However, if that rest * of branch is all ours and does not grow immediately from the inode * it's easier to cheat and just decrement partial->p. */if (p == chain + k - 1 && p > chain) {p->p--;} else {*top = *p->p;*p->p = 0;}write_unlock(&EXT2_I(inode)->i_meta_lock);while(partial > p){brelse(partial->bh);partial--;}no_top:return partial;}/** *ext2_free_data - free a list of data blocks *@inode:inode we are dealing with *@p:array of block numbers *@q:points immediately past the end of array * *We are freeing all blocks referred from that array (numbers are *stored as little-endian 32-bit) and updating @inode->i_blocks *appropriately. */static inline void ext2_free_data(struct inode *inode, __le32 *p, __le32 *q){unsigned long block_to_free = 0, count = 0;unsigned long nr;for ( ; p < q ; p++) {nr = le32_to_cpu(*p);if (nr) {*p = 0;/* accumulate blocks to free if they're contiguous */if (count == 0)goto free_this;/*this branch is to accumulate*/else if (block_to_free == nr - count)count++;else {ext2_free_blocks (inode, block_to_free, count);mark_inode_dirty(inode);free_this:block_to_free = nr;/*start address to free*/count = 1;}}}/*after break free the last one*/if (count > 0) {ext2_free_blocks (inode, block_to_free, count);mark_inode_dirty(inode);}}/** *ext2_free_branches - free an array of branches *@inode:inode we are dealing with *@p:array of block numbers *@q:pointer immediately past the end of array *@depth:depth of the branches to free * *We are freeing all blocks referred from these branches (numbers are *stored as little-endian 32-bit) and updating @inode->i_blocks *appropriately. */static void ext2_free_branches(struct inode *inode, __le32 *p, __le32 *q, int depth){struct buffer_head * bh;unsigned long nr;if (depth--) {int addr_per_block = EXT2_ADDR_PER_BLOCK(inode->i_sb);for ( ; p < q ; p++) {nr = le32_to_cpu(*p);if (!nr)continue;*p = 0;bh = sb_bread(inode->i_sb, nr);/* * A read failure? Report error and clear slot * (should be rare). */ if (!bh) {ext2_error(inode->i_sb, "ext2_free_branches","Read failure, inode=%ld, block=%ld",inode->i_ino, nr);continue;}ext2_free_branches(inode,   (__le32*)bh->b_data,   (__le32*)bh->b_data + addr_per_block,   depth);bforget(bh);ext2_free_blocks(inode, nr, 1);mark_inode_dirty(inode);}} elseext2_free_data(inode, p, q);}static void __ext2_truncate_blocks(struct inode *inode, loff_t offset){__le32 *i_data = EXT2_I(inode)->i_data;struct ext2_inode_info *ei = EXT2_I(inode);int addr_per_block = EXT2_ADDR_PER_BLOCK(inode->i_sb);int offsets[4];Indirect chain[4];Indirect *partial;__le32 nr = 0;int n;long iblock;unsigned blocksize;blocksize = inode->i_sb->s_blocksize;iblock = (offset + blocksize-1) >> EXT2_BLOCK_SIZE_BITS(inode->i_sb); /*offset in the block*/n = ext2_block_to_path(inode, iblock, offsets, NULL);if (n == 0)return;/* * From here we block out all ext2_get_block() callers who want to * modify the block allocation tree. */mutex_lock(&ei->truncate_mutex);if (n == 1) {/*free the direct blocks*/ext2_free_data(inode, i_data+offsets[0],i_data + EXT2_NDIR_BLOCKS);goto do_indirects;}partial = ext2_find_shared(inode, n, offsets, chain, &nr);/* Kill the top of shared branch (already detached) */if (nr) {if (partial == chain)mark_inode_dirty(inode);elsemark_buffer_dirty_inode(partial->bh, inode);ext2_free_branches(inode, &nr, &nr+1, (chain+n-1) - partial);}/* Clear the ends of indirect blocks on the shared branch */while (partial > chain) {ext2_free_branches(inode,   partial->p + 1,   (__le32*)partial->bh->b_data+addr_per_block,   (chain+n-1) - partial);mark_buffer_dirty_inode(partial->bh, inode);brelse (partial->bh);partial--;}do_indirects:/* Kill the remaining (whole) subtrees */switch (offsets[0]) {default:nr = i_data[EXT2_IND_BLOCK];if (nr) {i_data[EXT2_IND_BLOCK] = 0;mark_inode_dirty(inode);ext2_free_branches(inode, &nr, &nr+1, 1);}case EXT2_IND_BLOCK:nr = i_data[EXT2_DIND_BLOCK];if (nr) {i_data[EXT2_DIND_BLOCK] = 0;mark_inode_dirty(inode);ext2_free_branches(inode, &nr, &nr+1, 2);}case EXT2_DIND_BLOCK:nr = i_data[EXT2_TIND_BLOCK];if (nr) {i_data[EXT2_TIND_BLOCK] = 0;mark_inode_dirty(inode);ext2_free_branches(inode, &nr, &nr+1, 3);}case EXT2_TIND_BLOCK:;}ext2_discard_reservation(inode);mutex_unlock(&ei->truncate_mutex);}static void ext2_truncate_blocks(struct inode *inode, loff_t offset){/* * XXX: it seems like a bug here that we don't allow * IS_APPEND inode to have blocks-past-i_size trimmed off. * review and fix this. * * Also would be nice to be able to handle IO errors and such, * but that's probably too much to ask. */if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||    S_ISLNK(inode->i_mode)))return;if (ext2_inode_is_fast_symlink(inode))return;if (IS_APPEND(inode) || IS_IMMUTABLE(inode))return;__ext2_truncate_blocks(inode, offset); /*after check the conditions,do truncate*/}static int ext2_setsize(struct inode *inode, loff_t newsize){int error;if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||    S_ISLNK(inode->i_mode)))return -EINVAL;if (ext2_inode_is_fast_symlink(inode))return -EINVAL;if (IS_APPEND(inode) || IS_IMMUTABLE(inode))return -EPERM;inode_dio_wait(inode);/*disk io wait, for what?*/if (mapping_is_xip(inode->i_mapping))error = xip_truncate_page(inode->i_mapping, newsize);else if (test_opt(inode->i_sb, NOBH))error = nobh_truncate_page(inode->i_mapping,newsize, ext2_get_block);/*for norh truncate*/elseerror = block_truncate_page(inode->i_mapping,newsize, ext2_get_block);/*for data block truncate*/if (error)return error;truncate_setsize(inode, newsize);__ext2_truncate_blocks(inode, newsize);inode->i_mtime = inode->i_ctime = CURRENT_TIME_SEC;if (inode_needs_sync(inode)) {sync_mapping_buffers(inode->i_mapping);sync_inode_metadata(inode, 1);/*sync the data and metadata if needed*/} else {mark_inode_dirty(inode);}return 0;}static struct ext2_inode *ext2_get_inode(struct super_block *sb, ino_t ino,struct buffer_head **p){/*return inode pointer by input the inode number*/struct buffer_head * bh;unsigned long block_group;unsigned long block;unsigned long offset;struct ext2_group_desc * gdp;*p = NULL;if ((ino != EXT2_ROOT_INO && ino < EXT2_FIRST_INO(sb)) ||    ino > le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count))goto Einval;block_group = (ino - 1) / EXT2_INODES_PER_GROUP(sb); /*first find the block group*/gdp = ext2_get_group_desc(sb, block_group, NULL);if (!gdp)goto Egdp;/* * Figure out the offset within the block group inode table */offset = ((ino - 1) % EXT2_INODES_PER_GROUP(sb)) * EXT2_INODE_SIZE(sb);block = le32_to_cpu(gdp->bg_inode_table) +(offset >> EXT2_BLOCK_SIZE_BITS(sb)); /*which block contain the inode data*/if (!(bh = sb_bread(sb, block)))goto Eio;*p = bh; /*block buffer head*/offset &= (EXT2_BLOCK_SIZE(sb) - 1);/*offset in the block*/return (struct ext2_inode *) (bh->b_data + offset);Einval:ext2_error(sb, "ext2_get_inode", "bad inode number: %lu",   (unsigned long) ino);return ERR_PTR(-EINVAL);Eio:ext2_error(sb, "ext2_get_inode",   "unable to read inode block - inode=%lu, block=%lu",   (unsigned long) ino, block);Egdp:return ERR_PTR(-EIO);}void ext2_set_inode_flags(struct inode *inode){unsigned int flags = EXT2_I(inode)->i_flags;inode->i_flags &= ~(S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC);if (flags & EXT2_SYNC_FL)inode->i_flags |= S_SYNC;if (flags & EXT2_APPEND_FL)inode->i_flags |= S_APPEND;if (flags & EXT2_IMMUTABLE_FL)inode->i_flags |= S_IMMUTABLE;if (flags & EXT2_NOATIME_FL)inode->i_flags |= S_NOATIME;if (flags & EXT2_DIRSYNC_FL)inode->i_flags |= S_DIRSYNC;}/* Propagate flags from i_flags to EXT2_I(inode)->i_flags */void ext2_get_inode_flags(struct ext2_inode_info *ei){unsigned int flags = ei->vfs_inode.i_flags;ei->i_flags &= ~(EXT2_SYNC_FL|EXT2_APPEND_FL|EXT2_IMMUTABLE_FL|EXT2_NOATIME_FL|EXT2_DIRSYNC_FL);if (flags & S_SYNC)ei->i_flags |= EXT2_SYNC_FL;if (flags & S_APPEND)ei->i_flags |= EXT2_APPEND_FL;if (flags & S_IMMUTABLE)ei->i_flags |= EXT2_IMMUTABLE_FL;if (flags & S_NOATIME)ei->i_flags |= EXT2_NOATIME_FL;if (flags & S_DIRSYNC)ei->i_flags |= EXT2_DIRSYNC_FL;}struct inode *ext2_iget (struct super_block *sb, unsigned long ino){struct ext2_inode_info *ei;struct buffer_head * bh;struct ext2_inode *raw_inode;struct inode *inode;long ret = -EIO;int n;inode = iget_locked(sb, ino);/*get the inode from cache in system(not ext2 inode)*/if (!inode)return ERR_PTR(-ENOMEM);if (!(inode->i_state & I_NEW))return inode;ei = EXT2_I(inode);ei->i_block_alloc_info = NULL;raw_inode = ext2_get_inode(inode->i_sb, ino, &bh); /*the pointer to ext2 inode, read out, update inode*/if (IS_ERR(raw_inode)) {ret = PTR_ERR(raw_inode); goto bad_inode;}inode->i_mode = le16_to_cpu(raw_inode->i_mode);inode->i_uid = (uid_t)le16_to_cpu(raw_inode->i_uid_low);inode->i_gid = (gid_t)le16_to_cpu(raw_inode->i_gid_low);if (!(test_opt (inode->i_sb, NO_UID32))) {inode->i_uid |= le16_to_cpu(raw_inode->i_uid_high) << 16;inode->i_gid |= le16_to_cpu(raw_inode->i_gid_high) << 16;}set_nlink(inode, le16_to_cpu(raw_inode->i_links_count));inode->i_size = le32_to_cpu(raw_inode->i_size);inode->i_atime.tv_sec = (signed)le32_to_cpu(raw_inode->i_atime);inode->i_ctime.tv_sec = (signed)le32_to_cpu(raw_inode->i_ctime);inode->i_mtime.tv_sec = (signed)le32_to_cpu(raw_inode->i_mtime);inode->i_atime.tv_nsec = inode->i_mtime.tv_nsec = inode->i_ctime.tv_nsec = 0;ei->i_dtime = le32_to_cpu(raw_inode->i_dtime);/* We now have enough fields to check if the inode was active or not. * This is needed because nfsd might try to access dead inodes * the test is that same one that e2fsck uses * NeilBrown 1999oct15 */if (inode->i_nlink == 0 && (inode->i_mode == 0 || ei->i_dtime)) {/* this inode is deleted */brelse (bh);ret = -ESTALE;goto bad_inode;}inode->i_blocks = le32_to_cpu(raw_inode->i_blocks);ei->i_flags = le32_to_cpu(raw_inode->i_flags);ei->i_faddr = le32_to_cpu(raw_inode->i_faddr);ei->i_frag_no = raw_inode->i_frag;ei->i_frag_size = raw_inode->i_fsize;ei->i_file_acl = le32_to_cpu(raw_inode->i_file_acl);ei->i_dir_acl = 0;if (S_ISREG(inode->i_mode))inode->i_size |= ((__u64)le32_to_cpu(raw_inode->i_size_high)) << 32;elseei->i_dir_acl = le32_to_cpu(raw_inode->i_dir_acl);ei->i_dtime = 0;inode->i_generation = le32_to_cpu(raw_inode->i_generation);ei->i_state = 0;ei->i_block_group = (ino - 1) / EXT2_INODES_PER_GROUP(inode->i_sb);ei->i_dir_start_lookup = 0;/* * NOTE! The in-memory inode i_data array is in little-endian order * even on big-endian machines: we do NOT byteswap the block numbers! */for (n = 0; n < EXT2_N_BLOCKS; n++)ei->i_data[n] = raw_inode->i_block[n];if (S_ISREG(inode->i_mode)) {inode->i_op = &ext2_file_inode_operations;if (ext2_use_xip(inode->i_sb)) {inode->i_mapping->a_ops = &ext2_aops_xip;inode->i_fop = &ext2_xip_file_operations;} else if (test_opt(inode->i_sb, NOBH)) {inode->i_mapping->a_ops = &ext2_nobh_aops;inode->i_fop = &ext2_file_operations;} else {inode->i_mapping->a_ops = &ext2_aops;inode->i_fop = &ext2_file_operations;}} else if (S_ISDIR(inode->i_mode)) {inode->i_op = &ext2_dir_inode_operations;inode->i_fop = &ext2_dir_operations;if (test_opt(inode->i_sb, NOBH))inode->i_mapping->a_ops = &ext2_nobh_aops;elseinode->i_mapping->a_ops = &ext2_aops;} else if (S_ISLNK(inode->i_mode)) {if (ext2_inode_is_fast_symlink(inode)) {inode->i_op = &ext2_fast_symlink_inode_operations;nd_terminate_link(ei->i_data, inode->i_size,sizeof(ei->i_data) - 1);} else {inode->i_op = &ext2_symlink_inode_operations;if (test_opt(inode->i_sb, NOBH))inode->i_mapping->a_ops = &ext2_nobh_aops;elseinode->i_mapping->a_ops = &ext2_aops;}} else {inode->i_op = &ext2_special_inode_operations;if (raw_inode->i_block[0])init_special_inode(inode, inode->i_mode,   old_decode_dev(le32_to_cpu(raw_inode->i_block[0])));else init_special_inode(inode, inode->i_mode,   new_decode_dev(le32_to_cpu(raw_inode->i_block[1])));}brelse (bh);ext2_set_inode_flags(inode);unlock_new_inode(inode);return inode;bad_inode:iget_failed(inode);return ERR_PTR(ret);}static int __ext2_write_inode(struct inode *inode, int do_sync){struct ext2_inode_info *ei = EXT2_I(inode);struct super_block *sb = inode->i_sb;ino_t ino = inode->i_ino;uid_t uid = inode->i_uid;gid_t gid = inode->i_gid;struct buffer_head * bh;struct ext2_inode * raw_inode = ext2_get_inode(sb, ino, &bh);int n;int err = 0;if (IS_ERR(raw_inode)) return -EIO;/* For fields not not tracking in the in-memory inode, * initialise them to zero for new inodes. */if (ei->i_state & EXT2_STATE_NEW)memset(raw_inode, 0, EXT2_SB(sb)->s_inode_size);ext2_get_inode_flags(ei);raw_inode->i_mode = cpu_to_le16(inode->i_mode);if (!(test_opt(sb, NO_UID32))) {raw_inode->i_uid_low = cpu_to_le16(low_16_bits(uid));raw_inode->i_gid_low = cpu_to_le16(low_16_bits(gid));/* * Fix up interoperability with old kernels. Otherwise, old inodes get * re-used with the upper 16 bits of the uid/gid intact */if (!ei->i_dtime) {raw_inode->i_uid_high = cpu_to_le16(high_16_bits(uid));raw_inode->i_gid_high = cpu_to_le16(high_16_bits(gid));} else {raw_inode->i_uid_high = 0;raw_inode->i_gid_high = 0;}} else {raw_inode->i_uid_low = cpu_to_le16(fs_high2lowuid(uid));raw_inode->i_gid_low = cpu_to_le16(fs_high2lowgid(gid));raw_inode->i_uid_high = 0;raw_inode->i_gid_high = 0;}raw_inode->i_links_count = cpu_to_le16(inode->i_nlink);raw_inode->i_size = cpu_to_le32(inode->i_size);raw_inode->i_atime = cpu_to_le32(inode->i_atime.tv_sec);raw_inode->i_ctime = cpu_to_le32(inode->i_ctime.tv_sec);raw_inode->i_mtime = cpu_to_le32(inode->i_mtime.tv_sec);raw_inode->i_blocks = cpu_to_le32(inode->i_blocks);raw_inode->i_dtime = cpu_to_le32(ei->i_dtime);raw_inode->i_flags = cpu_to_le32(ei->i_flags);raw_inode->i_faddr = cpu_to_le32(ei->i_faddr);raw_inode->i_frag = ei->i_frag_no;raw_inode->i_fsize = ei->i_frag_size;raw_inode->i_file_acl = cpu_to_le32(ei->i_file_acl);if (!S_ISREG(inode->i_mode))raw_inode->i_dir_acl = cpu_to_le32(ei->i_dir_acl);else {raw_inode->i_size_high = cpu_to_le32(inode->i_size >> 32);if (inode->i_size > 0x7fffffffULL) {if (!EXT2_HAS_RO_COMPAT_FEATURE(sb,EXT2_FEATURE_RO_COMPAT_LARGE_FILE) ||    EXT2_SB(sb)->s_es->s_rev_level ==cpu_to_le32(EXT2_GOOD_OLD_REV)) {       /* If this is the first large file* created, add a flag to the superblock.*/spin_lock(&EXT2_SB(sb)->s_lock);ext2_update_dynamic_rev(sb);EXT2_SET_RO_COMPAT_FEATURE(sb,EXT2_FEATURE_RO_COMPAT_LARGE_FILE);spin_unlock(&EXT2_SB(sb)->s_lock);ext2_write_super(sb);}}}raw_inode->i_generation = cpu_to_le32(inode->i_generation);if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode)) {if (old_valid_dev(inode->i_rdev)) {raw_inode->i_block[0] =cpu_to_le32(old_encode_dev(inode->i_rdev));raw_inode->i_block[1] = 0;} else {raw_inode->i_block[0] = 0;raw_inode->i_block[1] =cpu_to_le32(new_encode_dev(inode->i_rdev));raw_inode->i_block[2] = 0;}} else for (n = 0; n < EXT2_N_BLOCKS; n++)raw_inode->i_block[n] = ei->i_data[n];mark_buffer_dirty(bh);/*when all raw inode updated, mark it buffer head drity*/if (do_sync) {sync_dirty_buffer(bh); /*sync if it is required*/if (buffer_req(bh) && !buffer_uptodate(bh)) {printk ("IO error syncing ext2 inode [%s:%08lx]\n",sb->s_id, (unsigned long) ino);err = -EIO;}}ei->i_state &= ~EXT2_STATE_NEW;brelse (bh);return err;}int ext2_write_inode(struct inode *inode, struct writeback_control *wbc){return __ext2_write_inode(inode, wbc->sync_mode == WB_SYNC_ALL); /*do sync*/}/*set some of the dentry attribute, and mark it dirty*/int ext2_setattr(struct dentry *dentry, struct iattr *iattr){struct inode *inode = dentry->d_inode;int error;error = inode_change_ok(inode, iattr);if (error)return error;if (is_quota_modification(inode, iattr))dquot_initialize(inode);if ((iattr->ia_valid & ATTR_UID && iattr->ia_uid != inode->i_uid) ||    (iattr->ia_valid & ATTR_GID && iattr->ia_gid != inode->i_gid)) {error = dquot_transfer(inode, iattr);if (error)return error;}if (iattr->ia_valid & ATTR_SIZE && iattr->ia_size != inode->i_size) {error = ext2_setsize(inode, iattr->ia_size);if (error)return error;}setattr_copy(inode, iattr);if (iattr->ia_valid & ATTR_MODE)error = ext2_acl_chmod(inode);mark_inode_dirty(inode);return error;}