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 // 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 number of direct blocks to allocate.
  */
 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
  *  @blks: the number of blocks need to allocate for direct blocks
  *  @new_blocks: on return it will store the new block numbers for
  *  the indirect blocks(if needed) and the first direct block,
  */
 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
  *  @indirect_blks: depth of the chain (number of blocks to allocate)
  *  @blks: number of allocated direct blocks
  *  @goal: preferred place for allocation
  *  @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);
             goto got_it;
         }
 
         if (err) {
             mutex_unlock(&ei->truncate_mutex);
             goto cleanup;
         }
     }
 
     /*
      * 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 total 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;
 
 }
 
 static int ext2_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
         unsigned flags, struct iomap *iomap, struct iomap *srcmap)
 {
     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->offset = (u64)first_block << blkbits;
     if (flags & IOMAP_DAX)
         iomap->dax_dev = sbi->s_daxdev;
     else
         iomap->bdev = inode->i_sb->s_bdev;
 
     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;
         if (flags & IOMAP_DAX)
             iomap->addr += sbi->s_dax_part_off;
         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,
 };
 
 int ext2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
         u64 start, u64 len)
 {
     int ret;
 
     inode_lock(inode);
     len = min_t(u64, len, i_size_read(inode));
     ret = iomap_fiemap(inode, fieinfo, start, len, &ext2_iomap_ops);
     inode_unlock(inode);
 
     return ret;
 }
 
 static int ext2_writepage(struct page *page, struct writeback_control *wbc)
 {
     return block_write_full_page(page, ext2_get_block, wbc);
 }
 
 static int ext2_read_folio(struct file *file, struct folio *folio)
 {
     return mpage_read_folio(folio, ext2_get_block);
 }
 
 static void ext2_readahead(struct readahead_control *rac)
 {
     mpage_readahead(rac, ext2_get_block);
 }
 
 static int
 ext2_write_begin(struct file *file, struct address_space *mapping,
         loff_t pos, unsigned len, struct page **pagep, void **fsdata)
 {
     int ret;
 
     ret = block_write_begin(mapping, pos, len, 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 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)
 {
     struct ext2_sb_info *sbi = EXT2_SB(mapping->host->i_sb);
 
     return dax_writeback_mapping_range(mapping, sbi->s_daxdev, wbc);
 }
 
 const struct address_space_operations ext2_aops = {
     .dirty_folio        = block_dirty_folio,
     .invalidate_folio   = block_invalidate_folio,
     .read_folio     = ext2_read_folio,
     .readahead      = ext2_readahead,
     .writepage      = ext2_writepage,
     .write_begin        = ext2_write_begin,
     .write_end      = ext2_write_end,
     .bmap           = ext2_bmap,
     .direct_IO      = ext2_direct_IO,
     .writepages     = ext2_writepages,
     .migrate_folio      = buffer_migrate_folio,
     .is_partially_uptodate  = block_is_partially_uptodate,
     .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,
     .dirty_folio        = noop_dirty_folio,
 };
 
 /*
  * 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);
 }
 
 /* mapping->invalidate_lock 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(&inode->i_mapping->invalidate_lock));
 #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);
             }
             fallthrough;
         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);
             }
             fallthrough;
         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);
             }
             break;
         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;
 
     filemap_invalidate_lock(inode->i_mapping);
     __ext2_truncate_blocks(inode, offset);
     filemap_invalidate_unlock(inode->i_mapping);
 }
 
 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 = dax_zero_range(inode, newsize,
                        PAGE_ALIGN(newsize) - newsize, NULL,
                        &ext2_iomap_ops);
     else
         error = block_truncate_page(inode->i_mapping,
                 newsize, ext2_get_block);
     if (error)
         return error;
 
     filemap_invalidate_lock(inode->i_mapping);
     truncate_setsize(inode, newsize);
     __ext2_truncate_blocks(inode, newsize);
     filemap_invalidate_unlock(inode->i_mapping);
 
     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
         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 = NULL;
     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 */
         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);
         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;
         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);
             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:
     brelse(bh);
     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 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_getattr(struct user_namespace *mnt_userns, const struct path *path,
          struct kstat *stat, u32 request_mask, unsigned int query_flags)
 {
     struct inode *inode = d_inode(path->dentry);
     struct ext2_inode_info *ei = EXT2_I(inode);
     unsigned int flags;
 
     flags = ei->i_flags & EXT2_FL_USER_VISIBLE;
     if (flags & EXT2_APPEND_FL)
         stat->attributes |= STATX_ATTR_APPEND;
     if (flags & EXT2_COMPR_FL)
         stat->attributes |= STATX_ATTR_COMPRESSED;
     if (flags & EXT2_IMMUTABLE_FL)
         stat->attributes |= STATX_ATTR_IMMUTABLE;
     if (flags & EXT2_NODUMP_FL)
         stat->attributes |= STATX_ATTR_NODUMP;
     stat->attributes_mask |= (STATX_ATTR_APPEND |
             STATX_ATTR_COMPRESSED |
             STATX_ATTR_ENCRYPTED |
             STATX_ATTR_IMMUTABLE |
             STATX_ATTR_NODUMP);
 
     generic_fillattr(&init_user_ns, inode, stat);
     return 0;
 }
 
 int ext2_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
          struct iattr *iattr)
 {
     struct inode *inode = d_inode(dentry);
     int error;
 
     error = setattr_prepare(&init_user_ns, dentry, iattr);
     if (error)
         return error;
 
     if (is_quota_modification(mnt_userns, inode, iattr)) {
         error = dquot_initialize(inode);
         if (error)
             return error;
     }
     if (i_uid_needs_update(mnt_userns, iattr, inode) ||
         i_gid_needs_update(mnt_userns, iattr, inode)) {
         error = dquot_transfer(mnt_userns, 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(&init_user_ns, inode, iattr);
     if (iattr->ia_valid & ATTR_MODE)
         error = posix_acl_chmod(&init_user_ns, inode, inode->i_mode);
     mark_inode_dirty(inode);
 
     return error;
 }

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