This removes nilfs_get_writer() and nilfs_put_writer() pair which is
used to retain a writable FS-instance for a period. The pair
functions were making up some kind of recursive lock, and they
eventually became obsolete by the bugfix patch ("nilfs2: fix circular
locking dependency of writer mutex").
This uses a reader/writer semaphore instead of the own lock.
Signed-off-by: Ryusuke Konishi <[email protected]>
---
fs/nilfs2/mdt.c | 10 +++++++---
fs/nilfs2/the_nilfs.c | 3 +--
fs/nilfs2/the_nilfs.h | 27 ++++++---------------------
3 files changed, 14 insertions(+), 26 deletions(-)
diff --git a/fs/nilfs2/mdt.c b/fs/nilfs2/mdt.c
index bb78745..c3eb539 100644
--- a/fs/nilfs2/mdt.c
+++ b/fs/nilfs2/mdt.c
@@ -402,6 +402,7 @@ nilfs_mdt_write_page(struct page *page, struct
writeback_control *wbc)
struct inode *inode = container_of(page->mapping,
struct inode, i_data);
struct super_block *sb = inode->i_sb;
+ struct the_nilfs *nilfs = NILFS_MDT(inode)->mi_nilfs;
struct nilfs_sb_info *writer = NULL;
int err = 0;
@@ -411,9 +412,12 @@ nilfs_mdt_write_page(struct page *page, struct
writeback_control *wbc)
if (page->mapping->assoc_mapping)
return 0; /* Do not request flush for shadow page cache */
if (!sb) {
- writer = nilfs_get_writer(NILFS_MDT(inode)->mi_nilfs);
- if (!writer)
+ down_read(&nilfs->ns_writer_sem);
+ writer = nilfs->ns_writer;
+ if (!writer) {
+ up_read(&nilfs->ns_writer_sem);
return -EROFS;
+ }
sb = writer->s_super;
}
@@ -423,7 +427,7 @@ nilfs_mdt_write_page(struct page *page, struct
writeback_control *wbc)
nilfs_flush_segment(sb, inode->i_ino);
if (writer)
- nilfs_put_writer(NILFS_MDT(inode)->mi_nilfs);
+ up_read(&nilfs->ns_writer_sem);
return err;
}
diff --git a/fs/nilfs2/the_nilfs.c b/fs/nilfs2/the_nilfs.c
index 7f65b3b..9befbc8 100644
--- a/fs/nilfs2/the_nilfs.c
+++ b/fs/nilfs2/the_nilfs.c
@@ -65,10 +65,9 @@ struct the_nilfs *alloc_nilfs(struct block_device *bdev)
nilfs->ns_bdev = bdev;
atomic_set(&nilfs->ns_count, 1);
- atomic_set(&nilfs->ns_writer_refcount, -1);
atomic_set(&nilfs->ns_ndirtyblks, 0);
init_rwsem(&nilfs->ns_sem);
- mutex_init(&nilfs->ns_writer_mutex);
+ init_rwsem(&nilfs->ns_writer_sem);
INIT_LIST_HEAD(&nilfs->ns_supers);
spin_lock_init(&nilfs->ns_last_segment_lock);
nilfs->ns_gc_inodes_h = NULL;
diff --git a/fs/nilfs2/the_nilfs.h b/fs/nilfs2/the_nilfs.h
index 30fe587..8732d37 100644
--- a/fs/nilfs2/the_nilfs.h
+++ b/fs/nilfs2/the_nilfs.h
@@ -47,8 +47,7 @@ enum {
* @ns_bdi: backing dev info
* @ns_writer: back pointer to writable nilfs_sb_info
* @ns_sem: semaphore for shared states
- * @ns_writer_mutex: mutex protecting ns_writer attach/detach
- * @ns_writer_refcount: number of referrers on ns_writer
+ * @ns_writer_sem: semaphore protecting ns_writer attach/detach
* @ns_sbh: buffer heads of on-disk super blocks
* @ns_sbp: pointers to super block data
* @ns_sbwtime: previous write time of super blocks
@@ -93,8 +92,7 @@ struct the_nilfs {
struct backing_dev_info *ns_bdi;
struct nilfs_sb_info *ns_writer;
struct rw_semaphore ns_sem;
- struct mutex ns_writer_mutex;
- atomic_t ns_writer_refcount;
+ struct rw_semaphore ns_writer_sem;
/*
* used for
@@ -208,34 +206,21 @@ static inline void get_nilfs(struct the_nilfs *nilfs)
atomic_inc(&nilfs->ns_count);
}
-static inline struct nilfs_sb_info *nilfs_get_writer(struct the_nilfs *nilfs)
-{
- if (atomic_inc_and_test(&nilfs->ns_writer_refcount))
- mutex_lock(&nilfs->ns_writer_mutex);
- return nilfs->ns_writer;
-}
-
-static inline void nilfs_put_writer(struct the_nilfs *nilfs)
-{
- if (atomic_add_negative(-1, &nilfs->ns_writer_refcount))
- mutex_unlock(&nilfs->ns_writer_mutex);
-}
-
static inline void
nilfs_attach_writer(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
{
- mutex_lock(&nilfs->ns_writer_mutex);
+ down_write(&nilfs->ns_writer_sem);
nilfs->ns_writer = sbi;
- mutex_unlock(&nilfs->ns_writer_mutex);
+ up_write(&nilfs->ns_writer_sem);
}
static inline void
nilfs_detach_writer(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
{
- mutex_lock(&nilfs->ns_writer_mutex);
+ down_write(&nilfs->ns_writer_sem);
if (sbi == nilfs->ns_writer)
nilfs->ns_writer = NULL;
- mutex_unlock(&nilfs->ns_writer_mutex);
+ up_write(&nilfs->ns_writer_sem);
}
static inline void
--
1.6.2
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