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Subject[RESEND][PATCH 5/9] Ext3: extended attribute sharing fixes and in-inode EAs
Ext3: factor our common xattr code; unnecessary lock

The ext3_xattr_set_handle2 and ext3_xattr_delete_inode functions contain
duplicate code to decrease the reference count of an xattr block. Move
this to a separate function.

Also we know we have exclusive access to the inode in
ext3_xattr_delete_inode; there is no need to grab the xattr_sem lock.

Signed-off-by: Andreas Gruenbacher <agruen@suse.de>

Index: linux-2.6.10/fs/ext3/xattr.c
===================================================================
--- linux-2.6.10.orig/fs/ext3/xattr.c
+++ linux-2.6.10/fs/ext3/xattr.c
@@ -356,6 +356,41 @@ static void ext3_xattr_update_super_bloc
}

/*
+ * Release the xattr block BH: If the reference count is > 1, decrement
+ * it; otherwise free the block.
+ */
+static void
+ext3_xattr_release_block(handle_t *handle, struct inode *inode,
+ struct buffer_head *bh)
+{
+ struct mb_cache_entry *ce = NULL;
+
+ ce = mb_cache_entry_get(ext3_xattr_cache, bh->b_bdev, bh->b_blocknr);
+ if (HDR(bh)->h_refcount == cpu_to_le32(1)) {
+ ea_bdebug(bh, "freeing");
+ if (ce)
+ mb_cache_entry_free(ce);
+ ext3_free_blocks(handle, inode, bh->b_blocknr, 1);
+ get_bh(bh);
+ ext3_forget(handle, 1, inode, bh, bh->b_blocknr);
+ } else {
+ if (ext3_journal_get_write_access(handle, bh) == 0) {
+ lock_buffer(bh);
+ HDR(bh)->h_refcount = cpu_to_le32(
+ le32_to_cpu(HDR(bh)->h_refcount) - 1);
+ ext3_journal_dirty_metadata(handle, bh);
+ if (IS_SYNC(inode))
+ handle->h_sync = 1;
+ DQUOT_FREE_BLOCK(inode, 1);
+ unlock_buffer(bh);
+ ea_bdebug(bh, "refcount now=%d",
+ le32_to_cpu(HDR(bh)->h_refcount) - 1);
+ }
+ if (ce)
+ mb_cache_entry_release(ce);
+ }
+}
+/*
* ext3_xattr_set_handle()
*
* Create, replace or remove an extended attribute for this inode. Buffer
@@ -733,37 +768,8 @@ getblk_failed:
/*
* If there was an old block, and we are no longer using it,
* release the old block.
- */
- ce = mb_cache_entry_get(ext3_xattr_cache, old_bh->b_bdev,
- old_bh->b_blocknr);
- if (HDR(old_bh)->h_refcount == cpu_to_le32(1)) {
- /* Free the old block. */
- ea_bdebug(old_bh, "freeing");
- ext3_free_blocks(handle, inode, old_bh->b_blocknr, 1);
-
- /* ext3_forget() calls bforget() for us, but we
- let our caller release old_bh, so we need to
- duplicate the handle before. */
- get_bh(old_bh);
- ext3_forget(handle, 1, inode, old_bh,old_bh->b_blocknr);
- if (ce) {
- mb_cache_entry_free(ce);
- ce = NULL;
- }
- } else {
- error = ext3_journal_get_write_access(handle, old_bh);
- if (error)
- goto cleanup;
- /* Decrement the refcount only. */
- lock_buffer(old_bh);
- HDR(old_bh)->h_refcount = cpu_to_le32(
- le32_to_cpu(HDR(old_bh)->h_refcount) - 1);
- DQUOT_FREE_BLOCK(inode, 1);
- ext3_journal_dirty_metadata(handle, old_bh);
- ea_bdebug(old_bh, "refcount now=%d",
- le32_to_cpu(HDR(old_bh)->h_refcount));
- unlock_buffer(old_bh);
- }
+ */
+ ext3_xattr_release_block(handle, inode, old_bh);
}

cleanup:
@@ -813,13 +819,13 @@ retry:
* ext3_xattr_delete_inode()
*
* Free extended attribute resources associated with this inode. This
- * is called immediately before an inode is freed.
+ * is called immediately before an inode is freed. We have exclusive
+ * access to the inode.
*/
void
ext3_xattr_delete_inode(handle_t *handle, struct inode *inode)
{
struct buffer_head *bh = NULL;
- struct mb_cache_entry *ce = NULL;

down_write(&EXT3_I(inode)->xattr_sem);
if (!EXT3_I(inode)->i_file_acl)
@@ -838,33 +844,10 @@ ext3_xattr_delete_inode(handle_t *handle
EXT3_I(inode)->i_file_acl);
goto cleanup;
}
- ce = mb_cache_entry_get(ext3_xattr_cache, bh->b_bdev, bh->b_blocknr);
- if (HDR(bh)->h_refcount == cpu_to_le32(1)) {
- if (ce) {
- mb_cache_entry_free(ce);
- ce = NULL;
- }
- ext3_free_blocks(handle, inode, EXT3_I(inode)->i_file_acl, 1);
- get_bh(bh);
- ext3_forget(handle, 1, inode, bh, EXT3_I(inode)->i_file_acl);
- } else {
- if (ext3_journal_get_write_access(handle, bh) != 0)
- goto cleanup;
- lock_buffer(bh);
- HDR(bh)->h_refcount = cpu_to_le32(
- le32_to_cpu(HDR(bh)->h_refcount) - 1);
- ext3_journal_dirty_metadata(handle, bh);
- if (IS_SYNC(inode))
- handle->h_sync = 1;
- DQUOT_FREE_BLOCK(inode, 1);
- unlock_buffer(bh);
- }
- ea_bdebug(bh, "refcount now=%d", le32_to_cpu(HDR(bh)->h_refcount) - 1);
+ ext3_xattr_release_block(handle, inode, bh);
EXT3_I(inode)->i_file_acl = 0;

cleanup:
- if (ce)
- mb_cache_entry_release(ce);
brelse(bh);
up_write(&EXT3_I(inode)->xattr_sem);
}
--
Andreas Gruenbacher <agruen@suse.de>
SUSE Labs, SUSE LINUX PRODUCTS GMBH
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