reiserfs: fix race in prealloc discard

[sfrench/cifs-2.6.git] / fs / reiserfs / bitmap.c

diff --git a/fs/reiserfs/bitmap.c b/fs/reiserfs/bitmap.c
index dc198bc64c61ddae9db7a936365a820d71abf2d0..edc8ef78b63fc204275725bf9c9d6b9a5b788a81 100644 (file)
--- a/fs/reiserfs/bitmap.c
+++ b/fs/reiserfs/bitmap.c
@@ -513,9 +513,17 @@ static void __discard_prealloc(struct reiserfs_transaction_handle *th,
                               "inode has negative prealloc blocks count.");
 #endif
        while (ei->i_prealloc_count > 0) {
-               reiserfs_free_prealloc_block(th, inode, ei->i_prealloc_block);
-               ei->i_prealloc_block++;
+               b_blocknr_t block_to_free;
+
+               /*
+                * reiserfs_free_prealloc_block can drop the write lock,
+                * which could allow another caller to free the same block.
+                * We can protect against it by modifying the prealloc
+                * state before calling it.
+                */
+               block_to_free = ei->i_prealloc_block++;
                ei->i_prealloc_count--;
+               reiserfs_free_prealloc_block(th, inode, block_to_free);
                dirty = 1;
        }
        if (dirty)
@@ -1128,7 +1136,7 @@ static int determine_prealloc_size(reiserfs_blocknr_hint_t * hint)
        hint->prealloc_size = 0;
 
        if (!hint->formatted_node && hint->preallocate) {
-               if (S_ISREG(hint->inode->i_mode)
+               if (S_ISREG(hint->inode->i_mode) && !IS_PRIVATE(hint->inode)
                    && hint->inode->i_size >=
                    REISERFS_SB(hint->th->t_super)->s_alloc_options.
                    preallocmin * hint->inode->i_sb->s_blocksize)