diff options
| author | Chuck Lever <chuck.lever@oracle.com> | 2023-07-25 14:31:04 -0400 |
|---|---|---|
| committer | Christian Brauner <brauner@kernel.org> | 2023-08-09 09:15:41 +0200 |
| commit | 2be4f05af71bb2a9958c5680c19e5a489636ff42 (patch) | |
| tree | 422fc12ee546561b1ccf87b66842201799e43f69 | |
| parent | bbaef7973dd017954419718ab2df526ae1f66e93 (diff) | |
libfs: Remove parent dentry locking in offset_iterate_dir()
Since offset_iterate_dir() does not walk the parent's d_subdir list
nor does it manipulate the parent's d_child, there doesn't seem to
be a reason to hold the parent's d_lock. The offset_ctx's xarray can
be sufficiently protected with just the RCU read lock.
Flame graph data captured during the git regression run shows a
20% reduction in CPU cycles consumed in offset_find_next().
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202307171640.e299f8d5-oliver.sang@intel.com
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Message-Id: <169030957098.157536.9938425508695693348.stgit@manet.1015granger.net>
Signed-off-by: Christian Brauner <brauner@kernel.org>
| -rw-r--r-- | fs/libfs.c | 11 |
1 files changed, 4 insertions, 7 deletions
diff --git a/fs/libfs.c b/fs/libfs.c index 3495f071093e..c78a48654a94 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -407,7 +407,7 @@ static struct dentry *offset_find_next(struct xa_state *xas) child = xas_next_entry(xas, U32_MAX); if (!child) goto out; - spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED); + spin_lock(&child->d_lock); if (simple_positive(child)) found = dget_dlock(child); spin_unlock(&child->d_lock); @@ -425,17 +425,14 @@ static bool offset_dir_emit(struct dir_context *ctx, struct dentry *dentry) inode->i_ino, fs_umode_to_dtype(inode->i_mode)); } -static void offset_iterate_dir(struct dentry *dir, struct dir_context *ctx) +static void offset_iterate_dir(struct inode *inode, struct dir_context *ctx) { - struct inode *inode = d_inode(dir); struct offset_ctx *so_ctx = inode->i_op->get_offset_ctx(inode); XA_STATE(xas, &so_ctx->xa, ctx->pos); struct dentry *dentry; while (true) { - spin_lock(&dir->d_lock); dentry = offset_find_next(&xas); - spin_unlock(&dir->d_lock); if (!dentry) break; @@ -465,7 +462,7 @@ static void offset_iterate_dir(struct dentry *dir, struct dir_context *ctx) * output buffer. * * On return, @ctx->pos contains an offset that will read the next entry - * in this directory when shmem_readdir() is called again with @ctx. + * in this directory when offset_readdir() is called again with @ctx. * * Return values: * %0 - Complete @@ -479,7 +476,7 @@ static int offset_readdir(struct file *file, struct dir_context *ctx) if (!dir_emit_dots(file, ctx)) return 0; - offset_iterate_dir(dir, ctx); + offset_iterate_dir(d_inode(dir), ctx); return 0; } |