ext2 reservations

Val's cross-port of the ext3 reservations code into ext2.

[mbligh@mbligh.org: Small type error for printk
[akpm@linux-foundation.org: fix types, sync with ext3]
[mbligh@mbligh.org: Bring ext2 reservations code in line with latest ext3]
[akpm@linux-foundation.org: kill noisy printk]
[akpm@linux-foundation.org: remember to dirty the gdp's block]
[akpm@linux-foundation.org: cross-port the missed 5dea5176e5c32ef9f0d1a41d28427b3bf6881b3a]
[akpm@linux-foundation.org: cross-port e6022603b9aa7d61d20b392e69edcdbbc1789969]
[akpm@linux-foundation.org: Port the omitted 08fb306fe63d98eb86e3b16f4cc21816fa47f18e]
[akpm@linux-foundation.org: Backport the missed 20acaa18d0c002fec180956f87adeb3f11f635a6]
[akpm@linux-foundation.org: fixes]
[cmm@us.ibm.com: fix reservation extension]
[bunk@stusta.de: make ext2_get_blocks() static]
[hugh@veritas.com: fix hang]
[hugh@veritas.com: ext2_new_blocks should reset the reservation window size]
[hugh@veritas.com: ext2 balloc: fix off-by-one against rsv_end]
[hugh@veritas.com: grp_goal 0 is a genuine goal (unlike -1), so ext2_try_to_allocate_with_rsv should treat it as such]
[hugh@veritas.com: rbtree usage cleanup]
[pbadari@us.ibm.com: Fix for ext2 reservation]
[bunk@kernel.org: remove fs/ext2/balloc.c:reserve_blocks()]
[hugh@veritas.com: ext2 balloc: use io_error label]
Cc: "Martin J. Bligh" <mbligh@mbligh.org>
Cc: Valerie Henson <val_henson@linux.intel.com>
Cc: Mingming Cao <cmm@us.ibm.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com>
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 308 insertions, 216 deletions

diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
index 84818176fd9d..b1ab32ab5a77 100644
--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -54,19 +54,6 @@ static inline int ext2_inode_is_fast_symlink(struct inode *inode)
 }
 
 /*
- * Called at each iput().
- *
- * The inode may be "bad" if ext2_read_inode() saw an error from
- * ext2_get_inode(), so we need to check that to avoid freeing random disk
- * blocks.
- */
-void ext2_put_inode(struct inode *inode)
-{
-        if (!is_bad_inode(inode))
-                ext2_discard_prealloc(inode);
-}
-
-/*
  * Called at the last iput() if i_nlink is zero.
  */
 void ext2_delete_inode (struct inode * inode)
@@ -89,61 +76,6 @@ no_delete:
         clear_inode(inode);     /* We must guarantee clearing of inode... */
 }
 
-void ext2_discard_prealloc (struct inode * inode)
-{
-#ifdef EXT2_PREALLOCATE
-        struct ext2_inode_info *ei = EXT2_I(inode);
-        write_lock(&ei->i_meta_lock);
-        if (ei->i_prealloc_count) {
-                unsigned short total = ei->i_prealloc_count;
-                unsigned long block = ei->i_prealloc_block;
-                ei->i_prealloc_count = 0;
-                ei->i_prealloc_block = 0;
-                write_unlock(&ei->i_meta_lock);
-                ext2_free_blocks (inode, block, total);
-                return;
-        } else
-                write_unlock(&ei->i_meta_lock);
-#endif
-}
-
-static int ext2_alloc_block (struct inode * inode, unsigned long goal, int *err)
-{
-#ifdef EXT2FS_DEBUG
-        static unsigned long alloc_hits, alloc_attempts;
-#endif
-        unsigned long result;
-
-
-#ifdef EXT2_PREALLOCATE
-        struct ext2_inode_info *ei = EXT2_I(inode);
-        write_lock(&ei->i_meta_lock);
-        if (ei->i_prealloc_count &&
-            (goal == ei->i_prealloc_block || goal + 1 == ei->i_prealloc_block))
-        {
-                result = ei->i_prealloc_block++;
-                ei->i_prealloc_count--;
-                write_unlock(&ei->i_meta_lock);
-                ext2_debug ("preallocation hit (%lu/%lu).\n",
-                            ++alloc_hits, ++alloc_attempts);
-        } else {
-                write_unlock(&ei->i_meta_lock);
-                ext2_discard_prealloc (inode);
-                ext2_debug ("preallocation miss (%lu/%lu).\n",
-                            alloc_hits, ++alloc_attempts);
-                if (S_ISREG(inode->i_mode))
-                        result = ext2_new_block (inode, goal, 
-                                 &ei->i_prealloc_count,
-                                 &ei->i_prealloc_block, err);
-                else
-                        result = ext2_new_block(inode, goal, NULL, NULL, err);
-        }
-#else
-        result = ext2_new_block (inode, goal, 0, 0, err);
-#endif
-        return result;
-}
-
 typedef struct {
         __le32  *p;
         __le32  key;
@@ -228,7 +160,8 @@ static int ext2_block_to_path(struct inode *inode,
                 ext2_warning (inode->i_sb, "ext2_block_to_path", "block > big");
         }
         if (boundary)
-                *boundary = (i_block & (ptrs - 1)) == (final - 1);
+                *boundary = final - 1 - (i_block & (ptrs - 1));
+
         return n;
 }
 
@@ -355,39 +288,129 @@ static unsigned long ext2_find_near(struct inode *inode, Indirect *ind)
  *      @block:  block we want
  *      @chain:  chain of indirect blocks
  *      @partial: pointer to the last triple within a chain
- *      @goal:  place to store the result.
  *
- *      Normally this function find the prefered place for block allocation,
- *      stores it in *@goal and returns zero. If the branch had been changed
- *      under us we return -EAGAIN.
+ *      Returns preferred place for a block (the goal).
  */
 
 static inline int ext2_find_goal(struct inode *inode,
                                  long block,
                                  Indirect chain[4],
-                                 Indirect *partial,
-                                 unsigned long *goal)
+                                 Indirect *partial)
 {
-        struct ext2_inode_info *ei = EXT2_I(inode);
-        write_lock(&ei->i_meta_lock);
-        if ((block == ei->i_next_alloc_block + 1) && ei->i_next_alloc_goal) {
-                ei->i_next_alloc_block++;
-                ei->i_next_alloc_goal++;
-        } 
-        if (verify_chain(chain, partial)) {
-                /*
-                 * try the heuristic for sequential allocation,
-                 * failing that at least try to get decent locality.
-                 */
-                if (block == ei->i_next_alloc_block)
-                        *goal = ei->i_next_alloc_goal;
-                if (!*goal)
-                        *goal = ext2_find_near(inode, partial);
-                write_unlock(&ei->i_meta_lock);
-                return 0;
+        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;
         }
-        write_unlock(&ei->i_meta_lock);
-        return -EAGAIN;
+
+        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);
+        return ret;
 }
 
 /**
@@ -416,39 +439,49 @@ static inline int ext2_find_goal(struct inode *inode,
  */
 
 static int ext2_alloc_branch(struct inode *inode,
-                             int num,
-                             unsigned long goal,
-                             int *offsets,
-                             Indirect *branch)
+                        int indirect_blks, int *blks, ext2_fsblk_t goal,
+                        int *offsets, Indirect *branch)
 {
         int blocksize = inode->i_sb->s_blocksize;
-        int n = 0;
-        int err;
-        int i;
-        int parent = ext2_alloc_block(inode, goal, &err);
-
-        branch[0].key = cpu_to_le32(parent);
-        if (parent) for (n = 1; n < num; n++) {
-                struct buffer_head *bh;
-                /* Allocate the next block */
-                int nr = ext2_alloc_block(inode, parent, &err);
-                if (!nr)
-                        break;
-                branch[n].key = cpu_to_le32(nr);
+        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.
+                 * 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, parent);
-                if (!bh) {
-                        err = -EIO;
-                        break;
-                }
+                bh = sb_getblk(inode->i_sb, new_blocks[n-1]);
+                branch[n].bh = bh;
                 lock_buffer(bh);
                 memset(bh->b_data, 0, blocksize);
-                branch[n].bh = bh;
                 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);
@@ -458,77 +491,68 @@ static int ext2_alloc_branch(struct inode *inode,
                  */
                 if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode))
                         sync_dirty_buffer(bh);
-                parent = nr;
         }
-        if (n == num)
-                return 0;
-
-        /* Allocation failed, free what we already allocated */
-        for (i = 1; i < n; i++)
-                bforget(branch[i].bh);
-        for (i = 0; i < n; i++)
-                ext2_free_blocks(inode, le32_to_cpu(branch[i].key), 1);
+        *blks = num;
         return err;
 }
 
 /**
- *      ext2_splice_branch - splice the allocated branch onto inode.
- *      @inode: owner
- *      @block: (logical) number of block we are adding
- *      @chain: chain of indirect blocks (with a missing link - see
- *              ext2_alloc_branch)
- *      @where: location of missing link
- *      @num:   number of blocks we are adding
+ * ext2_splice_branch - splice the allocated branch onto inode.
+ * @inode: owner
+ * @block: (logical) number of block we are adding
+ * @chain: chain of indirect blocks (with a missing link - see
+ *      ext2_alloc_branch)
+ * @where: location of missing link
+ * @num:   number of indirect blocks we are adding
+ * @blks:  number of direct blocks we are adding
  *
- *      This function verifies that chain (up to the missing link) had not
- *      changed, 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. Otherwise (== chain had been changed)
- *      we free the new blocks (forgetting their buffer_heads, indeed) and
- *      return -EAGAIN.
+ * 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 inline int ext2_splice_branch(struct inode *inode,
-                                     long block,
-                                     Indirect chain[4],
-                                     Indirect *where,
-                                     int num)
+static void ext2_splice_branch(struct inode *inode,
+                        long block, Indirect *where, int num, int blks)
 {
-        struct ext2_inode_info *ei = EXT2_I(inode);
         int i;
+        struct ext2_block_alloc_info *block_i;
+        ext2_fsblk_t current_block;
 
-        /* Verify that place we are splicing to is still there and vacant */
-
-        write_lock(&ei->i_meta_lock);
-        if (!verify_chain(chain, where-1) || *where->p)
-                goto changed;
+        block_i = EXT2_I(inode)->i_block_alloc_info;
 
+        /* XXX LOCKING probably should have i_meta_lock ?*/
         /* That's it */
 
         *where->p = where->key;
-        ei->i_next_alloc_block = block;
-        ei->i_next_alloc_goal = le32_to_cpu(where[num-1].key);
 
-        write_unlock(&ei->i_meta_lock);
+        /*
+         * 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++);
+        }
 
-        /* We are done with atomic stuff, now do the rest of housekeeping */
+        /*
+         * 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;
+        }
 
-        inode->i_ctime = CURRENT_TIME_SEC;
+        /* We are done with atomic stuff, now do the rest of housekeeping */
 
         /* had we spliced it onto indirect block? */
         if (where->bh)
                 mark_buffer_dirty_inode(where->bh, inode);
 
+        inode->i_ctime = CURRENT_TIME_SEC;
         mark_inode_dirty(inode);
-        return 0;
-
-changed:
-        write_unlock(&ei->i_meta_lock);
-        for (i = 1; i < num; i++)
-                bforget(where[i].bh);
-        for (i = 0; i < num; i++)
-                ext2_free_blocks(inode, le32_to_cpu(where[i].key), 1);
-        return -EAGAIN;
 }
 
 /*
@@ -542,64 +566,99 @@ changed:
  * 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.
+ *
+ * The BKL may not be held on entry here.  Be sure to take it early.
+ * return > 0, # of blocks mapped or allocated.
+ * return = 0, if plain lookup failed.
+ * return < 0, error case.
  */
-
-int ext2_get_block(struct inode *inode, sector_t iblock, struct buffer_head *bh_result, int create)
+static int ext2_get_blocks(struct inode *inode,
+                           sector_t iblock, unsigned long maxblocks,
+                           struct buffer_head *bh_result,
+                           int create)
 {
         int err = -EIO;
         int offsets[4];
         Indirect chain[4];
         Indirect *partial;
-        unsigned long goal;
-        int left;
-        int boundary = 0;
-        int depth = ext2_block_to_path(inode, iblock, offsets, &boundary);
+        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;
 
-        if (depth == 0)
-                goto out;
+        depth = ext2_block_to_path(inode,iblock,offsets,&blocks_to_boundary);
 
+        if (depth == 0)
+                return (err);
 reread:
         partial = ext2_get_branch(inode, depth, offsets, chain, &err);
 
         /* Simplest case - block found, no allocation needed */
         if (!partial) {
-got_it:
-                map_bh(bh_result, inode->i_sb, le32_to_cpu(chain[depth-1].key));
-                if (boundary)
-                        set_buffer_boundary(bh_result);
-                /* Clean up and exit */
-                partial = chain+depth-1; /* the whole chain */
-                goto cleanup;
+                first_block = le32_to_cpu(chain[depth - 1].key);
+                clear_buffer_new(bh_result); /* What's this do? */
+                count++;
+                /*map more blocks*/
+                while (count < maxblocks && count <= blocks_to_boundary) {
+                        ext2_fsblk_t blk;
+
+                        if (!verify_chain(chain, partial)) {
+                                /*
+                                 * 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.
+                                 */
+                                count = 0;
+                                goto changed;
+                        }
+                        blk = le32_to_cpu(*(chain[depth-1].p + count));
+                        if (blk == first_block + count)
+                                count++;
+                        else
+                                break;
+                }
+                goto got_it;
         }
 
         /* Next simple case - plain lookup or failed read of indirect block */
-        if (!create || err == -EIO) {
-cleanup:
-                while (partial > chain) {
-                        brelse(partial->bh);
-                        partial--;
-                }
-out:
-                return err;
-        }
+        if (!create || err == -EIO)
+                goto cleanup;
+
+        mutex_lock(&ei->truncate_mutex);
 
         /*
-         * Indirect block might be removed by truncate while we were
-         * reading it. Handling of that case (forget what we've got and
-         * reread) is taken out of the main path.
-         */
-        if (err == -EAGAIN)
-                goto changed;
+         * 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 = 0;
-        if (ext2_find_goal(inode, iblock, chain, partial, &goal) < 0)
-                goto changed;
+        goal = ext2_find_goal(inode, iblock, chain, partial);
 
-        left = (chain + depth) - partial;
-        err = ext2_alloc_branch(inode, left, goal,
-                                        offsets+(partial-chain), partial);
-        if (err)
+        /* the number of blocks need to allocate for [d,t]indirect blocks */
+        indirect_blks = (chain + depth) - partial - 1;
+        /*
+         * Next look up the indirect map to count the totoal number of
+         * direct blocks to allocate for this branch.
+         */
+        count = ext2_blks_to_allocate(partial, indirect_blks,
+                                        maxblocks, blocks_to_boundary);
+        /*
+         * XXX ???? Block out ext2_truncate while we alter the tree
+         */
+        err = ext2_alloc_branch(inode, indirect_blks, &count, goal,
+                                offsets + (partial - chain), partial);
+
+        if (err) {
+                mutex_unlock(&ei->truncate_mutex);
                 goto cleanup;
+        }
 
         if (ext2_use_xip(inode->i_sb)) {
                 /*
@@ -607,16 +666,28 @@ out:
                  */
                 err = ext2_clear_xip_target (inode,
                         le32_to_cpu(chain[depth-1].key));
-                if (err)
+                if (err) {
+                        mutex_unlock(&ei->truncate_mutex);
                         goto cleanup;
+                }
         }
 
-        if (ext2_splice_branch(inode, iblock, chain, partial, left) < 0)
-                goto changed;
-
+        ext2_splice_branch(inode, iblock, partial, indirect_blks, count);
+        mutex_unlock(&ei->truncate_mutex);
         set_buffer_new(bh_result);
-        goto got_it;
-
+got_it:
+        map_bh(bh_result, inode->i_sb, le32_to_cpu(chain[depth-1].key));
+        if (count > blocks_to_boundary)
+                set_buffer_boundary(bh_result);
+        err = count;
+        /* Clean up and exit */
+        partial = chain + depth - 1;    /* the whole chain */
+cleanup:
+        while (partial > chain) {
+                brelse(partial->bh);
+                partial--;
+        }
+        return err;
 changed:
         while (partial > chain) {
                 brelse(partial->bh);
@@ -625,6 +696,19 @@ changed:
         goto reread;
 }
 
+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;
+        int ret = ext2_get_blocks(inode, iblock, max_blocks,
+                              bh_result, create);
+        if (ret > 0) {
+                bh_result->b_size = (ret << inode->i_blkbits);
+                ret = 0;
+        }
+        return ret;
+
+}
+
 static int ext2_writepage(struct page *page, struct writeback_control *wbc)
 {
         return block_write_full_page(page, ext2_get_block, wbc);
@@ -913,9 +997,10 @@ static void ext2_free_branches(struct inode *inode, __le32 *p, __le32 *q, int de
                 ext2_free_data(inode, p, q);
 }
 
-void ext2_truncate (struct inode * inode)
+void ext2_truncate(struct inode *inode)
 {
         __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];
@@ -933,8 +1018,6 @@ void ext2_truncate (struct inode * inode)
         if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
                 return;
 
-        ext2_discard_prealloc(inode);
-
         blocksize = inode->i_sb->s_blocksize;
         iblock = (inode->i_size + blocksize-1)
                                         >> EXT2_BLOCK_SIZE_BITS(inode->i_sb);
@@ -952,6 +1035,12 @@ void ext2_truncate (struct inode * inode)
         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);
@@ -1004,6 +1093,10 @@ do_indirects:
                 case EXT2_TIND_BLOCK:
                         ;
         }
+
+        ext2_discard_reservation(inode);
+
+        mutex_unlock(&ei->truncate_mutex);
         inode->i_mtime = inode->i_ctime = CURRENT_TIME_SEC;
         if (inode_needs_sync(inode)) {
                 sync_mapping_buffers(inode->i_mapping);
@@ -1104,6 +1197,8 @@ void ext2_read_inode (struct inode * inode)
         ei->i_acl = EXT2_ACL_NOT_CACHED;
         ei->i_default_acl = EXT2_ACL_NOT_CACHED;
 #endif
+        ei->i_block_alloc_info = NULL;
+
         if (IS_ERR(raw_inode))
                 goto bad_inode;
 
@@ -1145,9 +1240,6 @@ void ext2_read_inode (struct inode * inode)
         ei->i_dtime = 0;
         inode->i_generation = le32_to_cpu(raw_inode->i_generation);
         ei->i_state = 0;
-        ei->i_next_alloc_block = 0;
-        ei->i_next_alloc_goal = 0;
-        ei->i_prealloc_count = 0;
         ei->i_block_group = (ino - 1) / EXT2_INODES_PER_GROUP(inode->i_sb);
         ei->i_dir_start_lookup = 0;