* @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.
+ * stores it in *@goal and returns zero.
*/
-static int ext3_find_goal(struct inode *inode, long block, Indirect chain[4],
- Indirect *partial, unsigned long *goal)
+static unsigned long ext3_find_goal(struct inode *inode, long block,
+ Indirect chain[4], Indirect *partial)
{
struct ext3_block_alloc_info *block_i = EXT3_I(inode)->i_block_alloc_info;
*/
if (block_i && (block == block_i->last_alloc_logical_block + 1)
&& (block_i->last_alloc_physical_block != 0)) {
- *goal = block_i->last_alloc_physical_block + 1;
- return 0;
+ return block_i->last_alloc_physical_block + 1;
}
- if (verify_chain(chain, partial)) {
- *goal = ext3_find_near(inode, partial);
- return 0;
- }
- return -EAGAIN;
+ return ext3_find_near(inode, partial);
}
/**
* @where: location of missing link
* @num: number of 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
+ * 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. Otherwise (== chain had been changed)
- * we free the new blocks (forgetting their buffer_heads, indeed) and
- * return -EAGAIN.
+ * chain to new block and return 0.
*/
static int ext3_splice_branch(handle_t *handle, struct inode *inode, long block,
if (err)
goto err_out;
}
- /* Verify that place we are splicing to is still there and vacant */
-
- if (!verify_chain(chain, where-1) || *where->p)
- /* Writer: end */
- goto changed;
-
/* That's it */
*where->p = where->key;
}
return err;
-changed:
- /*
- * AKPM: if where[i].bh isn't part of the current updating
- * transaction then we explode nastily. Test this code path.
- */
- jbd_debug(1, "the chain changed: try again\n");
- err = -EAGAIN;
-
err_out:
for (i = 1; i < num; i++) {
BUFFER_TRACE(where[i].bh, "call journal_forget");
ext3_journal_forget(handle, where[i].bh);
}
- /* For the normal collision cleanup case, we free up the blocks.
- * On genuine filesystem errors we don't even think about doing
- * that. */
- if (err == -EAGAIN)
- for (i = 0; i < num; i++)
- ext3_free_blocks(handle, inode,
- le32_to_cpu(where[i].key), 1);
return err;
}
unsigned long goal;
int left;
int boundary = 0;
- int depth = ext3_block_to_path(inode, iblock, offsets, &boundary);
+ const int depth = ext3_block_to_path(inode, iblock, offsets, &boundary);
struct ext3_inode_info *ei = EXT3_I(inode);
J_ASSERT(handle != NULL || create == 0);
if (depth == 0)
goto out;
-reread:
partial = ext3_get_branch(inode, depth, offsets, chain, &err);
/* Simplest case - block found, no allocation needed */
if (!partial) {
clear_buffer_new(bh_result);
-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;
+ goto got_it;
}
/* Next simple case - plain lookup or failed read of indirect block */
- if (!create || err == -EIO) {
-cleanup:
+ if (!create || err == -EIO)
+ goto cleanup;
+
+ down(&ei->truncate_sem);
+
+ /*
+ * 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) {
- BUFFER_TRACE(partial->bh, "call brelse");
brelse(partial->bh);
partial--;
}
- BUFFER_TRACE(bh_result, "returned");
-out:
- return err;
+ partial = ext3_get_branch(inode, depth, offsets, chain, &err);
+ if (!partial) {
+ up(&ei->truncate_sem);
+ if (err)
+ goto cleanup;
+ clear_buffer_new(bh_result);
+ goto got_it;
+ }
}
/*
- * 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;
-
- goal = 0;
- down(&ei->truncate_sem);
-
- /* lazy initialize the block allocation info here if necessary */
- if (S_ISREG(inode->i_mode) && (!ei->i_block_alloc_info)) {
+ * 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))
ext3_init_block_alloc_info(inode);
- }
- if (ext3_find_goal(inode, iblock, chain, partial, &goal) < 0) {
- up(&ei->truncate_sem);
- goto changed;
- }
+ goal = ext3_find_goal(inode, iblock, chain, partial);
left = (chain + depth) - partial;
* Block out ext3_truncate while we alter the tree
*/
err = ext3_alloc_branch(handle, inode, left, goal,
- offsets+(partial-chain), partial);
+ offsets + (partial - chain), partial);
- /* The ext3_splice_branch call will free and forget any buffers
+ /*
+ * The ext3_splice_branch call will free and forget any buffers
* on the new chain if there is a failure, but that risks using
* up transaction credits, especially for bitmaps where the
* credits cannot be returned. Can we handle this somehow? We
- * may need to return -EAGAIN upwards in the worst case. --sct */
+ * may need to return -EAGAIN upwards in the worst case. --sct
+ */
if (!err)
err = ext3_splice_branch(handle, inode, iblock, chain,
partial, left);
- /* i_disksize growing is protected by truncate_sem
- * don't forget to protect it if you're about to implement
- * concurrent ext3_get_block() -bzzz */
+ /*
+ * i_disksize growing is protected by truncate_sem. Don't forget to
+ * protect it if you're about to implement concurrent
+ * ext3_get_block() -bzzz
+ */
if (!err && extend_disksize && inode->i_size > ei->i_disksize)
ei->i_disksize = inode->i_size;
up(&ei->truncate_sem);
- if (err == -EAGAIN)
- goto changed;
if (err)
goto cleanup;
set_buffer_new(bh_result);
- goto got_it;
-
-changed:
+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 */
+cleanup:
while (partial > chain) {
- jbd_debug(1, "buffer chain changed, retrying\n");
- BUFFER_TRACE(partial->bh, "brelsing");
+ BUFFER_TRACE(partial->bh, "call brelse");
brelse(partial->bh);
partial--;
}
- goto reread;
+ BUFFER_TRACE(bh_result, "returned");
+out:
+ return err;
}
static int ext3_get_block(struct inode *inode, sector_t iblock,
projects / openwrt / staging / blogic.git / commitdiff