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-rw-r--r--fs/ext2/inode.c44
1 files changed, 33 insertions, 11 deletions
diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
index b43b9556..acf6788 100644
--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -590,9 +590,8 @@ static int ext2_get_blocks(struct inode *inode,
if (depth == 0)
return (err);
-reread:
- partial = ext2_get_branch(inode, depth, offsets, chain, &err);
+ 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);
@@ -602,15 +601,16 @@ reread:
while (count < maxblocks && count <= blocks_to_boundary) {
ext2_fsblk_t blk;
- if (!verify_chain(chain, partial)) {
+ 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;
- goto changed;
+ break;
}
blk = le32_to_cpu(*(chain[depth-1].p + count));
if (blk == first_block + count)
@@ -618,7 +618,8 @@ reread:
else
break;
}
- goto got_it;
+ if (err != -EAGAIN)
+ goto got_it;
}
/* Next simple case - plain lookup or failed read of indirect block */
@@ -626,6 +627,33 @@ reread:
goto cleanup;
mutex_lock(&ei->truncate_mutex);
+ /*
+ * If the indirect block is missing while we are reading
+ * the chain(ext3_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;
+ clear_buffer_new(bh_result);
+ goto got_it;
+ }
+ }
/*
* Okay, we need to do block allocation. Lazily initialize the block
@@ -683,12 +711,6 @@ cleanup:
partial--;
}
return err;
-changed:
- while (partial > chain) {
- brelse(partial->bh);
- partial--;
- }
- goto reread;
}
int ext2_get_block(struct inode *inode, sector_t iblock, struct buffer_head *bh_result, int create)
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