[PATCH 12/25] Unionfs: add un/likely conditionals on dentry ops

[Erez Zadok <ezk@cs.sunysb.edu>]

Signed-off-by: Erez Zadok <ezk@cs.sunysb.edu>
---
 fs/unionfs/dentry.c |   68 ++++++++++++++++++++++++++------------------------
 1 files changed, 35 insertions(+), 33 deletions(-)

diff --git a/fs/unionfs/dentry.c b/fs/unionfs/dentry.c
index 52bcb18..3f3a18d 100644
--- a/fs/unionfs/dentry.c
+++ b/fs/unionfs/dentry.c
@@ -45,7 +45,7 @@ static bool __unionfs_d_revalidate_one(struct dentry *dentry,
 	verify_locked(dentry);
 
 	/* if the dentry is unhashed, do NOT revalidate */
-	if (d_deleted(dentry)) {
+	if (unlikely(d_deleted(dentry))) {
 		dprintk(KERN_DEBUG "unionfs: unhashed dentry being "
 			"revalidated: %*s\n",
 			dentry->d_name.len, dentry->d_name.name);
@@ -53,7 +53,7 @@ static bool __unionfs_d_revalidate_one(struct dentry *dentry,
 	}
 
 	BUG_ON(dbstart(dentry) == -1);
-	if (dentry->d_inode)
+	if (likely(dentry->d_inode))
 		positive = 1;
 	dgen = atomic_read(&UNIONFS_D(dentry)->generation);
 	sbgen = atomic_read(&UNIONFS_SB(dentry->d_sb)->generation);
@@ -62,7 +62,7 @@ static bool __unionfs_d_revalidate_one(struct dentry *dentry,
 	 * revalidation to be done, because this file does not exist within
 	 * the namespace, and Unionfs operates on the namespace, not data.
 	 */
-	if (sbgen != dgen) {
+	if (unlikely(sbgen != dgen)) {
 		struct dentry *result;
 		int pdgen;
 
@@ -76,7 +76,7 @@ static bool __unionfs_d_revalidate_one(struct dentry *dentry,
 		/* Free the pointers for our inodes and this dentry. */
 		bstart = dbstart(dentry);
 		bend = dbend(dentry);
-		if (bstart >= 0) {
+		if (likely(bstart >= 0)) {
 			struct dentry *lower_dentry;
 			for (bindex = bstart; bindex <= bend; bindex++) {
 				lower_dentry =
@@ -89,7 +89,7 @@ static bool __unionfs_d_revalidate_one(struct dentry *dentry,
 		set_dbend(dentry, -1);
 
 		interpose_flag = INTERPOSE_REVAL_NEG;
-		if (positive) {
+		if (likely(positive)) {
 			interpose_flag = INTERPOSE_REVAL;
 			/*
 			 * During BRM, the VFS could already hold a lock on
@@ -97,14 +97,14 @@ static bool __unionfs_d_revalidate_one(struct dentry *dentry,
 			 * (deadlock), but if you lock it in this function,
 			 * then release it here too.
 			 */
-			if (!mutex_is_locked(&dentry->d_inode->i_mutex)) {
+			if (unlikely(!mutex_is_locked(&dentry->d_inode->i_mutex))) {
 				mutex_lock(&dentry->d_inode->i_mutex);
 				locked = 1;
 			}
 
 			bstart = ibstart(dentry->d_inode);
 			bend = ibend(dentry->d_inode);
-			if (bstart >= 0) {
+			if (likely(bstart >= 0)) {
 				struct inode *lower_inode;
 				for (bindex = bstart; bindex <= bend;
 				     bindex++) {
@@ -119,14 +119,14 @@ static bool __unionfs_d_revalidate_one(struct dentry *dentry,
 			UNIONFS_I(dentry->d_inode)->lower_inodes = NULL;
 			ibstart(dentry->d_inode) = -1;
 			ibend(dentry->d_inode) = -1;
-			if (locked)
+			if (unlikely(locked))
 				mutex_unlock(&dentry->d_inode->i_mutex);
 		}
 
 		result = unionfs_lookup_backend(dentry, &lowernd,
 						interpose_flag);
-		if (result) {
-			if (IS_ERR(result)) {
+		if (likely(result)) {
+			if (unlikely(IS_ERR(result))) {
 				valid = false;
 				goto out;
 			}
@@ -138,7 +138,7 @@ static bool __unionfs_d_revalidate_one(struct dentry *dentry,
 			dentry = result;
 		}
 
-		if (positive && UNIONFS_I(dentry->d_inode)->stale) {
+		if (unlikely(positive && UNIONFS_I(dentry->d_inode)->stale)) {
 			make_bad_inode(dentry->d_inode);
 			d_drop(dentry);
 			valid = false;
@@ -153,8 +153,8 @@ static bool __unionfs_d_revalidate_one(struct dentry *dentry,
 	BUG_ON(bstart == -1);
 	for (bindex = bstart; bindex <= bend; bindex++) {
 		lower_dentry = unionfs_lower_dentry_idx(dentry, bindex);
-		if (!lower_dentry || !lower_dentry->d_op
-		    || !lower_dentry->d_op->d_revalidate)
+		if (unlikely(!lower_dentry || !lower_dentry->d_op
+			     || !lower_dentry->d_op->d_revalidate))
 			continue;
 		/*
 		 * Don't pass nameidata to lower file system, because we
@@ -164,14 +164,15 @@ static bool __unionfs_d_revalidate_one(struct dentry *dentry,
 		 * invariants).  We will open lower files as and when needed
 		 * later on.
 		 */
-		if (!lower_dentry->d_op->d_revalidate(lower_dentry, NULL))
+		if (unlikely(!lower_dentry->d_op->d_revalidate(lower_dentry,
+							       NULL)))
 			valid = false;
 	}
 
-	if (!dentry->d_inode)
+	if (unlikely(!dentry->d_inode))
 		valid = false;
 
-	if (valid) {
+	if (likely(valid)) {
 		/*
 		 * If we get here, and we copy the meta-data from the lower
 		 * inode to our inode, then it is vital that we have already
@@ -200,32 +201,32 @@ bool is_newer_lower(const struct dentry *dentry)
 	struct inode *lower_inode;
 
 	/* ignore if we're called on semi-initialized dentries/inodes */
-	if (!dentry || !UNIONFS_D(dentry))
+	if (likely(!dentry || !UNIONFS_D(dentry)))
 		return false;
 	inode = dentry->d_inode;
-	if (!inode || !UNIONFS_I(inode) ||
-	    ibstart(inode) < 0 || ibend(inode) < 0)
+	if (unlikely(!inode || !UNIONFS_I(inode) ||
+		     ibstart(inode) < 0 || ibend(inode) < 0))
 		return false;
 
 	for (bindex = ibstart(inode); bindex <= ibend(inode); bindex++) {
 		lower_inode = unionfs_lower_inode_idx(inode, bindex);
-		if (!lower_inode)
+		if (unlikely(!lower_inode))
 			continue;
 		/*
 		 * We may want to apply other tests to determine if the
 		 * lower inode's data has changed, but checking for changed
 		 * ctime and mtime on the lower inode should be enough.
 		 */
-		if (timespec_compare(&inode->i_mtime,
-				     &lower_inode->i_mtime) < 0) {
+		if (unlikely(timespec_compare(&inode->i_mtime,
+					      &lower_inode->i_mtime) < 0)) {
 			printk("unionfs: new lower inode mtime "
 			       "(bindex=%d, name=%s)\n", bindex,
 			       dentry->d_name.name);
 			show_dinode_times(dentry);
 			return true; /* mtime changed! */
 		}
-		if (timespec_compare(&inode->i_ctime,
-				     &lower_inode->i_ctime) < 0) {
+		if (unlikely(timespec_compare(&inode->i_ctime,
+					      &lower_inode->i_ctime) < 0)) {
 			printk("unionfs: new lower inode ctime "
 			       "(bindex=%d, name=%s)\n", bindex,
 			       dentry->d_name.name);
@@ -293,7 +294,7 @@ bool __unionfs_d_revalidate_chain(struct dentry *dentry, struct nameidata *nd,
 	dtmp = dentry->d_parent;
 	dgen = atomic_read(&UNIONFS_D(dtmp)->generation);
 	/* XXX: should we check if is_newer_lower all the way up? */
-	if (is_newer_lower(dtmp)) {
+	if (unlikely(is_newer_lower(dtmp))) {
 		/*
 		 * Special case: the root dentry's generation number must
 		 * always be valid, but its lower inode times don't have to
@@ -327,7 +328,7 @@ bool __unionfs_d_revalidate_chain(struct dentry *dentry, struct nameidata *nd,
 	 * and short lived, so locality will be better.
 	 */
 	chain = kzalloc(chain_len * sizeof(struct dentry *), GFP_KERNEL);
-	if (!chain) {
+	if (unlikely(!chain)) {
 		printk("unionfs: no more memory in %s\n", __FUNCTION__);
 		goto out;
 	}
@@ -364,7 +365,7 @@ bool __unionfs_d_revalidate_chain(struct dentry *dentry, struct nameidata *nd,
 		}
 		unionfs_unlock_dentry(chain[i]);
 
-		if (!valid)
+		if (unlikely(!valid))
 			goto out_free;
 	}
 
@@ -373,7 +374,7 @@ out_this:
 	/* finally, lock this dentry and revalidate it */
 	verify_locked(dentry);
 	dgen = atomic_read(&UNIONFS_D(dentry)->generation);
-	if (is_newer_lower(dentry)) {
+	if (unlikely(is_newer_lower(dentry))) {
 		/* root dentry special case as aforementioned */
 		if (IS_ROOT(dentry))
 			unionfs_copy_attr_times(dentry->d_inode);
@@ -399,7 +400,7 @@ out_this:
 	 * which __unionfs_d_revalidate_one has incremented.  Note: the "if"
 	 * test below does not depend on whether chain_len was 0 or greater.
 	 */
-	if (valid && sbgen != dgen)
+	if (unlikely(valid && sbgen != dgen))
 		for (bindex = dbstart(dentry);
 		     bindex <= dbend(dentry);
 		     bindex++)
@@ -425,7 +426,7 @@ static int unionfs_d_revalidate(struct dentry *dentry, struct nameidata *nd)
 	unionfs_lock_dentry(dentry);
 	err = __unionfs_d_revalidate_chain(dentry, nd, false);
 	unionfs_unlock_dentry(dentry);
-	if (err > 0) { /* true==1: dentry is valid */
+	if (likely(err > 0)) { /* true==1: dentry is valid */
 		unionfs_check_dentry(dentry);
 		unionfs_check_nd(nd);
 	}
@@ -447,11 +448,11 @@ static void unionfs_d_release(struct dentry *dentry)
 
 	unionfs_check_dentry(dentry);
 	/* this could be a negative dentry, so check first */
-	if (!UNIONFS_D(dentry)) {
+	if (unlikely(!UNIONFS_D(dentry))) {
 		printk(KERN_DEBUG "unionfs: dentry without private data: %.*s\n",
 		       dentry->d_name.len, dentry->d_name.name);
 		goto out;
-	} else if (dbstart(dentry) < 0) {
+	} else if (unlikely(dbstart(dentry) < 0)) {
 		/* this is due to a failed lookup */
 		printk(KERN_DEBUG "unionfs: dentry without lower "
 		       "dentries: %.*s\n",
@@ -466,7 +467,8 @@ static void unionfs_d_release(struct dentry *dentry)
 		dput(unionfs_lower_dentry_idx(dentry, bindex));
 		unionfs_set_lower_dentry_idx(dentry, bindex, NULL);
 		/* NULL lower mnt is ok if this is a negative dentry */
-		if (!dentry->d_inode && !unionfs_lower_mnt_idx(dentry,bindex))
+		if (unlikely(!dentry->d_inode &&
+			     !unionfs_lower_mnt_idx(dentry,bindex)))
 			continue;
 		unionfs_mntput(dentry, bindex);
 		unionfs_set_lower_mnt_idx(dentry, bindex, NULL);
-- 
1.5.2.2

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