ext4: fix data corruption regression by reverting commit 6de9843dab3f

[pandora-kernel.git] / fs / ext4 / inode.c

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 1a86282..9c8cf81 100644 (file)
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2502,6 +2502,7 @@ static int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
                 * for partial write.
                 */
                set_buffer_new(bh);
+               set_buffer_mapped(bh);
        }
        return 0;
 }
@@ -4429,8 +4430,8 @@ void ext4_truncate(struct inode *inode)
        Indirect chain[4];
        Indirect *partial;
        __le32 nr = 0;
-       int n;
-       ext4_lblk_t last_block;
+       int n = 0;
+       ext4_lblk_t last_block, max_block;
        unsigned blocksize = inode->i_sb->s_blocksize;
 
        trace_ext4_truncate_enter(inode);
@@ -4455,14 +4456,18 @@ void ext4_truncate(struct inode *inode)
 
        last_block = (inode->i_size + blocksize-1)
                                        >> EXT4_BLOCK_SIZE_BITS(inode->i_sb);
+       max_block = (EXT4_SB(inode->i_sb)->s_bitmap_maxbytes + blocksize-1)
+                                       >> EXT4_BLOCK_SIZE_BITS(inode->i_sb);
 
        if (inode->i_size & (blocksize - 1))
                if (ext4_block_truncate_page(handle, mapping, inode->i_size))
                        goto out_stop;
 
-       n = ext4_block_to_path(inode, last_block, offsets, NULL);
-       if (n == 0)
-               goto out_stop;  /* error */
+       if (last_block != max_block) {
+               n = ext4_block_to_path(inode, last_block, offsets, NULL);
+               if (n == 0)
+                       goto out_stop;  /* error */
+       }
 
        /*
         * OK.  This truncate is going to happen.  We add the inode to the
@@ -4493,7 +4498,13 @@ void ext4_truncate(struct inode *inode)
         */
        ei->i_disksize = inode->i_size;
 
-       if (n == 1) {           /* direct blocks */
+       if (last_block == max_block) {
+               /*
+                * It is unnecessary to free any data blocks if last_block is
+                * equal to the indirect block limit.
+                */
+               goto out_unlock;
+       } else if (n == 1) {            /* direct blocks */
                ext4_free_data(handle, inode, NULL, i_data+offsets[0],
                               i_data + EXT4_NDIR_BLOCKS);
                goto do_indirects;
@@ -4553,6 +4564,7 @@ do_indirects:
                ;
        }
 
+out_unlock:
        up_write(&ei->i_data_sem);
        inode->i_mtime = inode->i_ctime = ext4_current_time(inode);
        ext4_mark_inode_dirty(handle, inode);
@@ -5398,13 +5410,12 @@ static int ext4_indirect_trans_blocks(struct inode *inode, int nrblocks,
        /* if nrblocks are contiguous */
        if (chunk) {
                /*
-                * With N contiguous data blocks, it need at most
-                * N/EXT4_ADDR_PER_BLOCK(inode->i_sb) indirect blocks
-                * 2 dindirect blocks
-                * 1 tindirect block
+                * With N contiguous data blocks, we need at most
+                * N/EXT4_ADDR_PER_BLOCK(inode->i_sb) + 1 indirect blocks,
+                * 2 dindirect blocks, and 1 tindirect block
                 */
-               indirects = nrblocks / EXT4_ADDR_PER_BLOCK(inode->i_sb);
-               return indirects + 3;
+               return DIV_ROUND_UP(nrblocks,
+                                   EXT4_ADDR_PER_BLOCK(inode->i_sb)) + 4;
        }
        /*
         * if nrblocks are not contiguous, worse case, each block touch