From: Jan Kara <jack@xxxxxxx>
This patch is needed in pnfs tree for exofs.
Currently, we initialize inode->i_mapping.backing_dev_info to the bdi of device
sb->s_bdev points to. However there is quite a big number of filesystems that
do not set sb->s_bdev (because they do not have one) but do set sb->s_bdi.
These filesystems would generally benefit from setting
inode->i_mapping.backing_dev_info to their s_bdi because otherwise their inodes
would point to default_backing_dev_info and thus dirty inode tracking would
happen there. So change inode initialization code to use sb->s_bdi if it
is available.
Signed-off-by: Jan Kara <jack@xxxxxxx>
---
fs/inode.c | 22 ++++++++++++++--------
1 files changed, 14 insertions(+), 8 deletions(-)
diff --git a/fs/inode.c b/fs/inode.c
index 8646433..e415be4 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -172,15 +172,21 @@ int inode_init_always(struct super_block *sb, struct inode *inode)
mapping->writeback_index = 0;
/*
- * If the block_device provides a backing_dev_info for client
- * inodes then use that. Otherwise the inode share the bdev's
- * backing_dev_info.
+ * If the filesystem provides a backing_dev_info for client inodes
+ * then use that. Otherwise inodes share default_backing_dev_info.
*/
- if (sb->s_bdev) {
- struct backing_dev_info *bdi;
-
- bdi = sb->s_bdev->bd_inode->i_mapping->backing_dev_info;
- mapping->backing_dev_info = bdi;
+ if (sb->s_bdi && sb->s_bdi != &noop_backing_dev_info) {
+ /*
+ * Catch cases where filesystem might be bitten by using s_bdi
+ * instead of sb->s_bdev. Can be removed in 2.6.38.
+ */
+ if (sb->s_bdev) {
+ struct backing_dev_info *bdi =
+ sb->s_bdev->bd_inode->i_mapping->backing_dev_info;
+ WARN(bdi != sb->s_bdi, "s_bdev bdi %s != s_bdi %s\n",
+ bdi->name, sb->s_bdi->name);
+ }
+ mapping->backing_dev_info = sb->s_bdi;
}
inode->i_private = NULL;
inode->i_mapping = mapping;
--
1.7.2
--
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