Skip to content
Snippets Groups Projects
Select Git revision
  • fa59b92d299f2787e6bae1ff078ee0982e80211f
  • master default
  • android-container
  • nanopc-t4
  • for-kernelci
  • WIP-syscall
  • v4.16-rc5
  • v4.16-rc4
  • v4.16-rc3
  • v4.16-rc2
  • v4.16-rc1
  • v4.15
  • v4.15-rc9
  • v4.15-rc8
  • v4.15-rc7
  • v4.15-rc6
  • v4.15-rc5
  • v4.15-rc4
  • v4.15-rc3
  • v4.15-rc2
  • v4.15-rc1
  • v4.14
  • v4.14-rc8
  • v4.14-rc7
  • v4.14-rc6
  • v4.14-rc5
26 results

mcryptd.c

Blame
  • inode.c 47.08 KiB
    // SPDX-License-Identifier: GPL-2.0
    /*
     *  linux/fs/ext2/inode.c
     *
     * Copyright (C) 1992, 1993, 1994, 1995
     * Remy Card (card@masi.ibp.fr)
     * 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
     * 	(sct@dcs.ed.ac.uk), 1993, 1998
     *  Big-endian to little-endian byte-swapping/bitmaps by
     *        David S. Miller (davem@caip.rutgers.edu), 1995
     *  64-bit file support on 64-bit platforms by Jakub Jelinek
     * 	(jj@sunsite.ms.mff.cuni.cz)
     *
     *  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/dax.h>
    #include <linux/blkdev.h>
    #include <linux/quotaops.h>
    #include <linux/writeback.h>
    #include <linux/buffer_head.h>
    #include <linux/mpage.h>
    #include <linux/fiemap.h>
    #include <linux/iomap.h>
    #include <linux/namei.h>
    #include <linux/uio.h>
    #include "ext2.h"
    #include "acl.h"
    #include "xattr.h"
    
    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) {
    		truncate_pagecache(inode, inode->i_size);
    		ext2_truncate_blocks(inode, inode->i_size);
    	}
    }
    
    /*
     * Called at the last iput() if i_nlink is zero.
     */
    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;
    		dquot_initialize(inode);
    	} else {
    		dquot_drop(inode);
    	}
    
    	truncate_inode_pages_final(&inode->i_data);
    
    	if (want_delete) {
    		sb_start_intwrite(inode->i_sb);
    		/* set dtime */
    		EXT2_I(inode)->i_dtime	= ktime_get_real_seconds();
    		mark_inode_dirty(inode);
    		__ext2_write_inode(inode, inode_needs_sync(inode));
    		/* truncate to 0 */
    		inode->i_size = 0;
    		if (inode->i_blocks)
    			ext2_truncate_blocks(inode, 0);
    		ext2_xattr_delete_inode(inode);
    	}
    
    	invalidate_inode_buffers(inode);
    	clear_inode(inode);
    
    	ext2_discard_reservation(inode);
    	rsv = EXT2_I(inode)->i_block_alloc_info;
    	EXT2_I(inode)->i_block_alloc_info = NULL;
    	if (unlikely(rsv))
    		kfree(rsv);
    
    	if (want_delete) {
    		ext2_free_inode(inode);
    		sb_end_intwrite(inode->i_sb);
    	}
    }
    
    typedef struct {
    	__le32	*p;
    	__le32	key;
    	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);
    	int ptrs_bits = EXT2_ADDR_PER_BLOCK_BITS(inode->i_sb);
    	const long direct_blocks = EXT2_NDIR_BLOCKS,
    		indirect_blocks = ptrs,
    		double_blocks = (1 << (ptrs_bits * 2));
    	int n = 0;
    	int final = 0;
    
    	if (i_block < 0) {
    		ext2_msg(inode->i_sb, KERN_WARNING,
    			"warning: %s: block < 0", __func__);
    	} else if (i_block < direct_blocks) {
    		offsets[n++] = i_block;
    		final = direct_blocks;
    	} else if ( (i_block -= direct_blocks) < indirect_blocks) {
    		offsets[n++] = EXT2_IND_BLOCK;
    		offsets[n++] = i_block;
    		final = ptrs;
    	} 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 {
    		ext2_msg(inode->i_sb, KERN_WARNING,
    			"warning: %s: block is too big", __func__);
    	}
    	if (boundary)
    		*boundary = final - 1 - (i_block & (ptrs - 1));
    
    	return n;
    }
    
    /**
     *	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;
    	struct buffer_head *bh;
    
    	*err = 0;
    	/* i_data is not going away, no lock needed */
    	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);
    		if (!verify_chain(chain, p))
    			goto changed;
    		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--)
    		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);
    	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 int
    ext2_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;
    		else
    			count += blocks_to_boundary + 1;
    		return count;
    	}
    
    	count++;
    	while (count < blks && count <= blocks_to_boundary
    		&& le32_to_cpu(*(branch[0].p + count)) == 0) {
    		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;
    
    	while (1) {
    		count = target;
    		/* allocating blocks for indirect blocks and direct blocks */
    		current_block = ext2_new_blocks(inode,goal,&count,err);
    		if (*err)
    			goto failed_out;
    
    		target -= count;
    		/* allocate blocks for indirect blocks */
    		while (index < indirect_blks && count) {
    			new_blocks[index++] = current_block++;
    			count--;
    		}
    
    		if (count > 0)
    			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);
    	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]);
    		if (unlikely(!bh)) {
    			err = -ENOMEM;
    			goto failed;
    		}
    		branch[n].bh = bh;
    		lock_buffer(bh);
    		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;
    		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;
    
    failed:
    	for (i = 1; i < n; i++)
    		bforget(branch[i].bh);
    	for (i = 0; i < indirect_blks; i++)
    		ext2_free_blocks(inode, new_blocks[i], 1);
    	ext2_free_blocks(inode, new_blocks[i], 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;
    
    	/*
    	 * Update the host buffer_head or inode to point to more just allocated
    	 * direct blocks blocks
    	 */
    	if (num == 0 && blks > 1) {
    		current_block = le32_to_cpu(where->key) + 1;
    		for (i = 1; i < blks; i++)
    			*(where->p + i ) = cpu_to_le32(current_block++);
    	}
    
    	/*
    	 * 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(inode);
    	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,
    			   u32 *bno, bool *new, bool *boundary,
    			   int create)
    {
    	int err;
    	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);
    
    	depth = ext2_block_to_path(inode,iblock,offsets,&blocks_to_boundary);
    
    	if (depth == 0)
    		return -EIO;
    
    	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);
    		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;
    				partial = chain + depth - 1;
    				break;
    			}
    			blk = le32_to_cpu(*(chain[depth-1].p + count));
    			if (blk == first_block + count)
    				count++;
    			else
    				break;
    		}
    		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;
    			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 (IS_DAX(inode)) {
    		/*
    		 * We must unmap blocks before zeroing so that writeback cannot
    		 * overwrite zeros with stale data from block device page cache.
    		 */
    		clean_bdev_aliases(inode->i_sb->s_bdev,
    				   le32_to_cpu(chain[depth-1].key),
    				   count);
    		/*
    		 * block must be initialised before we put it in the tree
    		 * so that it's not found by another thread before it's
    		 * initialised
    		 */
    		err = sb_issue_zeroout(inode->i_sb,
    				le32_to_cpu(chain[depth-1].key), count,
    				GFP_NOFS);
    		if (err) {
    			mutex_unlock(&ei->truncate_mutex);
    			goto cleanup;
    		}
    	}
    	*new = true;
    
    	ext2_splice_branch(inode, iblock, partial, indirect_blks, count);
    	mutex_unlock(&ei->truncate_mutex);
    got_it:
    	if (count > blocks_to_boundary)
    		*boundary = true;
    	err = count;
    	/* Clean up and exit */
    	partial = chain + depth - 1;	/* the whole chain */
    cleanup:
    	while (partial > chain) {
    		brelse(partial->bh);
    		partial--;
    	}
    	if (err > 0)
    		*bno = le32_to_cpu(chain[depth-1].key);
    	return err;
    }
    
    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;
    	bool new = false, boundary = false;
    	u32 bno;
    	int ret;
    
    	ret = ext2_get_blocks(inode, iblock, max_blocks, &bno, &new, &boundary,
    			create);
    	if (ret <= 0)
    		return ret;
    
    	map_bh(bh_result, inode->i_sb, bno);
    	bh_result->b_size = (ret << inode->i_blkbits);
    	if (new)
    		set_buffer_new(bh_result);
    	if (boundary)
    		set_buffer_boundary(bh_result);
    	return 0;
    
    }
    
    #ifdef CONFIG_FS_DAX
    static int ext2_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
    		unsigned flags, struct iomap *iomap)
    {
    	unsigned int blkbits = inode->i_blkbits;
    	unsigned long first_block = offset >> blkbits;
    	unsigned long max_blocks = (length + (1 << blkbits) - 1) >> blkbits;
    	struct ext2_sb_info *sbi = EXT2_SB(inode->i_sb);
    	bool new = false, boundary = false;
    	u32 bno;
    	int ret;
    
    	ret = ext2_get_blocks(inode, first_block, max_blocks,
    			&bno, &new, &boundary, flags & IOMAP_WRITE);
    	if (ret < 0)
    		return ret;
    
    	iomap->flags = 0;
    	iomap->bdev = inode->i_sb->s_bdev;
    	iomap->offset = (u64)first_block << blkbits;
    	iomap->dax_dev = sbi->s_daxdev;
    
    	if (ret == 0) {
    		iomap->type = IOMAP_HOLE;
    		iomap->addr = IOMAP_NULL_ADDR;
    		iomap->length = 1 << blkbits;
    	} else {
    		iomap->type = IOMAP_MAPPED;
    		iomap->addr = (u64)bno << blkbits;
    		iomap->length = (u64)ret << blkbits;
    		iomap->flags |= IOMAP_F_MERGED;
    	}
    
    	if (new)
    		iomap->flags |= IOMAP_F_NEW;
    	return 0;
    }
    
    static int
    ext2_iomap_end(struct inode *inode, loff_t offset, loff_t length,
    		ssize_t written, unsigned flags, struct iomap *iomap)
    {
    	if (iomap->type == IOMAP_MAPPED &&
    	    written < length &&
    	    (flags & IOMAP_WRITE))
    		ext2_write_failed(inode->i_mapping, offset + length);
    	return 0;
    }
    
    const struct iomap_ops ext2_iomap_ops = {
    	.iomap_begin		= ext2_iomap_begin,
    	.iomap_end		= ext2_iomap_end,
    };
    #else
    /* Define empty ops for !CONFIG_FS_DAX case to avoid ugly ifdefs */
    const struct iomap_ops ext2_iomap_ops;
    #endif /* CONFIG_FS_DAX */
    
    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);
    }
    
    static int ext2_readpage(struct file *file, struct page *page)
    {
    	return mpage_readpage(page, ext2_get_block);
    }
    
    static int
    ext2_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 int
    ext2_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 int
    ext2_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_t
    ext2_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
    {
    	struct file *file = iocb->ki_filp;
    	struct address_space *mapping = file->f_mapping;
    	struct inode *inode = mapping->host;
    	size_t count = iov_iter_count(iter);
    	loff_t offset = iocb->ki_pos;
    	ssize_t ret;
    
    	ret = blockdev_direct_IO(iocb, inode, iter, ext2_get_block);
    	if (ret < 0 && iov_iter_rw(iter) == WRITE)
    		ext2_write_failed(mapping, offset + count);
    	return ret;
    }
    
    static int
    ext2_writepages(struct address_space *mapping, struct writeback_control *wbc)
    {
    	return mpage_writepages(mapping, wbc, ext2_get_block);
    }
    
    static int
    ext2_dax_writepages(struct address_space *mapping, struct writeback_control *wbc)
    {
    	return dax_writeback_mapping_range(mapping,
    			mapping->host->i_sb->s_bdev, wbc);
    }
    
    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_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,
    };
    
    static const struct address_space_operations ext2_dax_aops = {
    	.writepages		= ext2_dax_writepages,
    	.direct_IO		= noop_direct_IO,
    	.set_page_dirty		= noop_set_page_dirty,
    	.invalidatepage		= noop_invalidatepage,
    };
    
    /*
     * 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;
    			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;
    				count = 1;
    			}
    		}
    	}
    	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);
    		}
    	} else
    		ext2_free_data(inode, p, q);
    }
    
    /* dax_sem must be held when calling this function */
    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);
    
    #ifdef CONFIG_FS_DAX
    	WARN_ON(!rwsem_is_locked(&ei->dax_sem));
    #endif
    
    	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) {
    		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);
    		else
    			mark_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)
    {
    	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;
    
    	dax_sem_down_write(EXT2_I(inode));
    	__ext2_truncate_blocks(inode, offset);
    	dax_sem_up_write(EXT2_I(inode));
    }
    
    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);
    
    	if (IS_DAX(inode)) {
    		error = iomap_zero_range(inode, newsize,
    					 PAGE_ALIGN(newsize) - newsize, NULL,
    					 &ext2_iomap_ops);
    	} else if (test_opt(inode->i_sb, NOBH))
    		error = nobh_truncate_page(inode->i_mapping,
    				newsize, ext2_get_block);
    	else
    		error = block_truncate_page(inode->i_mapping,
    				newsize, ext2_get_block);
    	if (error)
    		return error;
    
    	dax_sem_down_write(EXT2_I(inode));
    	truncate_setsize(inode, newsize);
    	__ext2_truncate_blocks(inode, newsize);
    	dax_sem_up_write(EXT2_I(inode));
    
    	inode->i_mtime = inode->i_ctime = current_time(inode);
    	if (inode_needs_sync(inode)) {
    		sync_mapping_buffers(inode->i_mapping);
    		sync_inode_metadata(inode, 1);
    	} 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)
    {
    	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);
    	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));
    	if (!(bh = sb_bread(sb, block)))
    		goto Eio;
    
    	*p = bh;
    	offset &= (EXT2_BLOCK_SIZE(sb) - 1);
    	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 | S_DAX);
    	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;
    	if (test_opt(inode->i_sb, DAX) && S_ISREG(inode->i_mode))
    		inode->i_flags |= S_DAX;
    }
    
    void ext2_set_file_ops(struct inode *inode)
    {
    	inode->i_op = &ext2_file_inode_operations;
    	inode->i_fop = &ext2_file_operations;
    	if (IS_DAX(inode))
    		inode->i_mapping->a_ops = &ext2_dax_aops;
    	else if (test_opt(inode->i_sb, NOBH))
    		inode->i_mapping->a_ops = &ext2_nobh_aops;
    	else
    		inode->i_mapping->a_ops = &ext2_aops;
    }
    
    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;
    	uid_t i_uid;
    	gid_t i_gid;
    
    	inode = iget_locked(sb, ino);
    	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);
    	if (IS_ERR(raw_inode)) {
    		ret = PTR_ERR(raw_inode);
     		goto bad_inode;
    	}
    
    	inode->i_mode = le16_to_cpu(raw_inode->i_mode);
    	i_uid = (uid_t)le16_to_cpu(raw_inode->i_uid_low);
    	i_gid = (gid_t)le16_to_cpu(raw_inode->i_gid_low);
    	if (!(test_opt (inode->i_sb, NO_UID32))) {
    		i_uid |= le16_to_cpu(raw_inode->i_uid_high) << 16;
    		i_gid |= le16_to_cpu(raw_inode->i_gid_high) << 16;
    	}
    	i_uid_write(inode, i_uid);
    	i_gid_write(inode, i_gid);
    	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);
    	ext2_set_inode_flags(inode);
    	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 (ei->i_file_acl &&
    	    !ext2_data_block_valid(EXT2_SB(sb), ei->i_file_acl, 1)) {
    		ext2_error(sb, "ext2_iget", "bad extended attribute block %u",
    			   ei->i_file_acl);
    		brelse(bh);
    		ret = -EFSCORRUPTED;
    		goto bad_inode;
    	}
    
    	if (S_ISREG(inode->i_mode))
    		inode->i_size |= ((__u64)le32_to_cpu(raw_inode->i_size_high)) << 32;
    	else
    		ei->i_dir_acl = le32_to_cpu(raw_inode->i_dir_acl);
    	if (i_size_read(inode) < 0) {
    		ret = -EFSCORRUPTED;
    		goto bad_inode;
    	}
    	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)) {
    		ext2_set_file_ops(inode);
    	} 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;
    		else
    			inode->i_mapping->a_ops = &ext2_aops;
    	} else if (S_ISLNK(inode->i_mode)) {
    		if (ext2_inode_is_fast_symlink(inode)) {
    			inode->i_link = (char *)ei->i_data;
    			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;
    			inode_nohighmem(inode);
    			if (test_opt(inode->i_sb, NOBH))
    				inode->i_mapping->a_ops = &ext2_nobh_aops;
    			else
    				inode->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);
    	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 = i_uid_read(inode);
    	gid_t gid = i_gid_read(inode);
    	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);
    
    	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_sync_super(sb, EXT2_SB(sb)->s_es, 1);
    			}
    		}
    	}
    	
    	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);
    	if (do_sync) {
    		sync_dirty_buffer(bh);
    		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);
    }
    
    int ext2_setattr(struct dentry *dentry, struct iattr *iattr)
    {
    	struct inode *inode = d_inode(dentry);
    	int error;
    
    	error = setattr_prepare(dentry, iattr);
    	if (error)
    		return error;
    
    	if (is_quota_modification(inode, iattr)) {
    		error = dquot_initialize(inode);
    		if (error)
    			return error;
    	}
    	if ((iattr->ia_valid & ATTR_UID && !uid_eq(iattr->ia_uid, inode->i_uid)) ||
    	    (iattr->ia_valid & ATTR_GID && !gid_eq(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 = posix_acl_chmod(inode, inode->i_mode);
    	mark_inode_dirty(inode);
    
    	return error;
    }