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| author | Minchan Kim <minchan@kernel.org> | 2021-11-18 15:00:08 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-11-24 13:55:16 +0100 |
| commit | 393c3714081a53795bbff0e985d24146def6f57f (patch) | |
| tree | 188134895692753a0862a1cbd9a8466d56a4245b /fs/kernfs/mount.c | |
| parent | 136057256686de39cc3a07c2e39ef6bc43003ff6 (diff) | |
| download | linux-393c3714081a53795bbff0e985d24146def6f57f.tar.gz linux-393c3714081a53795bbff0e985d24146def6f57f.tar.bz2 linux-393c3714081a53795bbff0e985d24146def6f57f.zip | |
kernfs: switch global kernfs_rwsem lock to per-fs lock
The kernfs implementation has big lock granularity(kernfs_rwsem) so
every kernfs-based(e.g., sysfs, cgroup) fs are able to compete the
lock. It makes trouble for some cases to wait the global lock
for a long time even though they are totally independent contexts
each other.
A general example is process A goes under direct reclaim with holding
the lock when it accessed the file in sysfs and process B is waiting
the lock with exclusive mode and then process C is waiting the lock
until process B could finish the job after it gets the lock from
process A.
This patch switches the global kernfs_rwsem to per-fs lock, which
put the rwsem into kernfs_root.
Suggested-by: Tejun Heo <tj@kernel.org>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Minchan Kim <minchan@kernel.org>
Link: https://lore.kernel.org/r/20211118230008.2679780-1-minchan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/kernfs/mount.c')
| -rw-r--r-- | fs/kernfs/mount.c | 15 |
1 files changed, 9 insertions, 6 deletions
diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c index f2f909d09f52..cfa79715fc1a 100644 --- a/fs/kernfs/mount.c +++ b/fs/kernfs/mount.c @@ -236,6 +236,7 @@ struct dentry *kernfs_node_dentry(struct kernfs_node *kn, static int kernfs_fill_super(struct super_block *sb, struct kernfs_fs_context *kfc) { struct kernfs_super_info *info = kernfs_info(sb); + struct kernfs_root *kf_root = kfc->root; struct inode *inode; struct dentry *root; @@ -255,9 +256,9 @@ static int kernfs_fill_super(struct super_block *sb, struct kernfs_fs_context *k sb->s_shrink.seeks = 0; /* get root inode, initialize and unlock it */ - down_read(&kernfs_rwsem); + down_read(&kf_root->kernfs_rwsem); inode = kernfs_get_inode(sb, info->root->kn); - up_read(&kernfs_rwsem); + up_read(&kf_root->kernfs_rwsem); if (!inode) { pr_debug("kernfs: could not get root inode\n"); return -ENOMEM; @@ -334,6 +335,7 @@ int kernfs_get_tree(struct fs_context *fc) if (!sb->s_root) { struct kernfs_super_info *info = kernfs_info(sb); + struct kernfs_root *root = kfc->root; kfc->new_sb_created = true; @@ -344,9 +346,9 @@ int kernfs_get_tree(struct fs_context *fc) } sb->s_flags |= SB_ACTIVE; - down_write(&kernfs_rwsem); + down_write(&root->kernfs_rwsem); list_add(&info->node, &info->root->supers); - up_write(&kernfs_rwsem); + up_write(&root->kernfs_rwsem); } fc->root = dget(sb->s_root); @@ -371,10 +373,11 @@ void kernfs_free_fs_context(struct fs_context *fc) void kernfs_kill_sb(struct super_block *sb) { struct kernfs_super_info *info = kernfs_info(sb); + struct kernfs_root *root = info->root; - down_write(&kernfs_rwsem); + down_write(&root->kernfs_rwsem); list_del(&info->node); - up_write(&kernfs_rwsem); + up_write(&root->kernfs_rwsem); /* * Remove the superblock from fs_supers/s_instances |