From fb045adb99d9b7c562dc7fef834857f78249daa1 Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Fri, 7 Jan 2011 17:49:55 +1100 Subject: fs: dcache reduce branches in lookup path Reduce some branches and memory accesses in dcache lookup by adding dentry flags to indicate common d_ops are set, rather than having to check them. This saves a pointer memory access (dentry->d_op) in common path lookup situations, and saves another pointer load and branch in cases where we have d_op but not the particular operation. Patched with: git grep -E '[.>]([[:space:]])*d_op([[:space:]])*=' | xargs sed -e 's/\([^\t ]*\)->d_op = \(.*\);/d_set_d_op(\1, \2);/' -e 's/\([^\t ]*\)\.d_op = \(.*\);/d_set_d_op(\&\1, \2);/' -i Signed-off-by: Nick Piggin --- fs/dcache.c | 30 ++++++++++++++++++++++++++---- 1 file changed, 26 insertions(+), 4 deletions(-) (limited to 'fs/dcache.c') diff --git a/fs/dcache.c b/fs/dcache.c index 1d5cf511e1c..f9693da3efb 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -398,7 +398,7 @@ repeat: return; } - if (dentry->d_op && dentry->d_op->d_delete) { + if (dentry->d_flags & DCACHE_OP_DELETE) { if (dentry->d_op->d_delete(dentry)) goto kill_it; } @@ -1301,6 +1301,28 @@ struct dentry *d_alloc_name(struct dentry *parent, const char *name) } EXPORT_SYMBOL(d_alloc_name); +void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op) +{ + BUG_ON(dentry->d_op); + BUG_ON(dentry->d_flags & (DCACHE_OP_HASH | + DCACHE_OP_COMPARE | + DCACHE_OP_REVALIDATE | + DCACHE_OP_DELETE )); + dentry->d_op = op; + if (!op) + return; + if (op->d_hash) + dentry->d_flags |= DCACHE_OP_HASH; + if (op->d_compare) + dentry->d_flags |= DCACHE_OP_COMPARE; + if (op->d_revalidate) + dentry->d_flags |= DCACHE_OP_REVALIDATE; + if (op->d_delete) + dentry->d_flags |= DCACHE_OP_DELETE; + +} +EXPORT_SYMBOL(d_set_d_op); + static void __d_instantiate(struct dentry *dentry, struct inode *inode) { spin_lock(&dentry->d_lock); @@ -1731,7 +1753,7 @@ seqretry: */ if (read_seqcount_retry(&dentry->d_seq, *seq)) goto seqretry; - if (parent->d_op && parent->d_op->d_compare) { + if (parent->d_flags & DCACHE_OP_COMPARE) { if (parent->d_op->d_compare(parent, *inode, dentry, i, tlen, tname, name)) @@ -1846,7 +1868,7 @@ struct dentry *__d_lookup(struct dentry *parent, struct qstr *name) */ tlen = dentry->d_name.len; tname = dentry->d_name.name; - if (parent->d_op && parent->d_op->d_compare) { + if (parent->d_flags & DCACHE_OP_COMPARE) { if (parent->d_op->d_compare(parent, parent->d_inode, dentry, dentry->d_inode, tlen, tname, name)) @@ -1887,7 +1909,7 @@ struct dentry *d_hash_and_lookup(struct dentry *dir, struct qstr *name) * routine may choose to leave the hash value unchanged. */ name->hash = full_name_hash(name->name, name->len); - if (dir->d_op && dir->d_op->d_hash) { + if (dir->d_flags & DCACHE_OP_HASH) { if (dir->d_op->d_hash(dir, dir->d_inode, name) < 0) goto out; } -- cgit v1.2.3-18-g5258