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authorChristoph Hellwig <hch@lst.de>2010-10-04 14:25:33 +0200
committerJens Axboe <jaxboe@fusionio.com>2010-10-04 14:25:33 +0200
commitaaead25b954879e1a708ff2f3602f494c18d20b5 (patch)
tree85c42d7c603bba80035079400764bffd27b2ff0e /fs/fs-writeback.c
parentc6ea21e35bf3691cad59647c771e6606067f627d (diff)
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writeback: always use sb->s_bdi for writeback purposes
We currently use struct backing_dev_info for various different purposes. Originally it was introduced to describe a backing device which includes an unplug and congestion function and various bits of readahead information and VM-relevant flags. We're also using for tracking dirty inodes for writeback. To make writeback properly find all inodes we need to only access the per-filesystem backing_device pointed to by the superblock in ->s_bdi inside the writeback code, and not the instances pointeded to by inode->i_mapping->backing_dev which can be overriden by special devices or might not be set at all by some filesystems. Long term we should split out the writeback-relevant bits of struct backing_device_info (which includes more than the current bdi_writeback) and only point to it from the superblock while leaving the traditional backing device as a separate structure that can be overriden by devices. The one exception for now is the block device filesystem which really wants different writeback contexts for it's different (internal) inodes to handle the writeout more efficiently. For now we do this with a hack in fs-writeback.c because we're so late in the cycle, but in the future I plan to replace this with a superblock method that allows for multiple writeback contexts per filesystem. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Diffstat (limited to 'fs/fs-writeback.c')
-rw-r--r--fs/fs-writeback.c19
1 files changed, 4 insertions, 15 deletions
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 5581122bd2c..ab38fef1c9a 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -72,22 +72,11 @@ int writeback_in_progress(struct backing_dev_info *bdi)
static inline struct backing_dev_info *inode_to_bdi(struct inode *inode)
{
struct super_block *sb = inode->i_sb;
- struct backing_dev_info *bdi = inode->i_mapping->backing_dev_info;
- /*
- * For inodes on standard filesystems, we use superblock's bdi. For
- * inodes on virtual filesystems, we want to use inode mapping's bdi
- * because they can possibly point to something useful (think about
- * block_dev filesystem).
- */
- if (sb->s_bdi && sb->s_bdi != &noop_backing_dev_info) {
- /* Some device inodes could play dirty tricks. Catch them... */
- WARN(bdi != sb->s_bdi && bdi_cap_writeback_dirty(bdi),
- "Dirtiable inode bdi %s != sb bdi %s\n",
- bdi->name, sb->s_bdi->name);
- return sb->s_bdi;
- }
- return bdi;
+ if (strcmp(sb->s_type->name, "bdev") == 0)
+ return inode->i_mapping->backing_dev_info;
+
+ return sb->s_bdi;
}
static void bdi_queue_work(struct backing_dev_info *bdi,