From 0145acc202ca613b23b5383e55df3c32a92ad1bf Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Fri, 2 Mar 2012 14:32:59 -0800 Subject: vfs: uninline full_name_hash() .. and also use it in lookup_one_len() rather than open-coding it. There aren't any performance-critical users, so inlining it is silly. But it wouldn't matter if it wasn't for the fact that the word-at-a-time dentry name patches want to conditionally replace the function, and uninlining it sets the stage for that. So again, this is a preparatory patch that doesn't change any semantics, and only prepares for a much cleaner and testable word-at-a-time dentry name accessor patch. Signed-off-by: Linus Torvalds --- fs/namei.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) (limited to 'fs/namei.c') diff --git a/fs/namei.c b/fs/namei.c index a780ea5..ec72fa1 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -1374,6 +1374,14 @@ static inline int can_lookup(struct inode *inode) return 1; } +unsigned int full_name_hash(const unsigned char *name, unsigned int len) +{ + unsigned long hash = init_name_hash(); + while (len--) + hash = partial_name_hash(*name++, hash); + return end_name_hash(hash); +} + /* * Name resolution. * This is the basic name resolution function, turning a pathname into @@ -1775,24 +1783,21 @@ static struct dentry *lookup_hash(struct nameidata *nd) struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) { struct qstr this; - unsigned long hash; unsigned int c; WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); this.name = name; this.len = len; + this.hash = full_name_hash(name, len); if (!len) return ERR_PTR(-EACCES); - hash = init_name_hash(); while (len--) { c = *(const unsigned char *)name++; if (c == '/' || c == '\0') return ERR_PTR(-EACCES); - hash = partial_name_hash(c, hash); } - this.hash = end_name_hash(hash); /* * See if the low-level filesystem might want * to use its own hash.. -- cgit v1.1 From 200e9ef7ab51f3dce4f35f90ea458cf43ea83bb8 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Fri, 2 Mar 2012 14:49:24 -0800 Subject: vfs: split up name hashing in link_path_walk() into helper function The code in link_path_walk() that finds out the length and the hash of the next path component is some of the hottest code in the kernel. And I have a version of it that does things at the full width of the CPU wordsize at a time, but that means that we *really* want to split it up into a separate helper function. So this re-organizes the code a bit and splits the hashing part into a helper function called "hash_name()". It returns the length of the pathname component, while at the same time computing and writing the hash to the appropriate location. The code generation is slightly changed by this patch, but generally for the better - and the added abstraction actually makes the code easier to read too. And the new interface is well suited for replacing just the "hash_name()" function with alternative implementations. Signed-off-by: Linus Torvalds --- fs/namei.c | 52 ++++++++++++++++++++++++++++++++++------------------ 1 file changed, 34 insertions(+), 18 deletions(-) (limited to 'fs/namei.c') diff --git a/fs/namei.c b/fs/namei.c index ec72fa1..71807dc 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -1383,6 +1383,25 @@ unsigned int full_name_hash(const unsigned char *name, unsigned int len) } /* + * We know there's a real path component here of at least + * one character. + */ +static inline unsigned long hash_name(const char *name, unsigned int *hashp) +{ + unsigned long hash = init_name_hash(); + unsigned long len = 0, c; + + c = (unsigned char)*name; + do { + len++; + hash = partial_name_hash(c, hash); + c = (unsigned char)name[len]; + } while (c && c != '/'); + *hashp = end_name_hash(hash); + return len; +} + +/* * Name resolution. * This is the basic name resolution function, turning a pathname into * the final dentry. We expect 'base' to be positive and a directory. @@ -1402,31 +1421,22 @@ static int link_path_walk(const char *name, struct nameidata *nd) /* At this point we know we have a real path component. */ for(;;) { - unsigned long hash; struct qstr this; - unsigned int c; + long len; int type; err = may_lookup(nd); if (err) break; + len = hash_name(name, &this.hash); this.name = name; - c = *(const unsigned char *)name; - - hash = init_name_hash(); - do { - name++; - hash = partial_name_hash(c, hash); - c = *(const unsigned char *)name; - } while (c && (c != '/')); - this.len = name - (const char *) this.name; - this.hash = end_name_hash(hash); + this.len = len; type = LAST_NORM; - if (this.name[0] == '.') switch (this.len) { + if (name[0] == '.') switch (len) { case 2: - if (this.name[1] == '.') { + if (name[1] == '.') { type = LAST_DOTDOT; nd->flags |= LOOKUP_JUMPED; } @@ -1445,12 +1455,18 @@ static int link_path_walk(const char *name, struct nameidata *nd) } } - /* remove trailing slashes? */ - if (!c) + if (!name[len]) goto last_component; - while (*++name == '/'); - if (!*name) + /* + * If it wasn't NUL, we know it was '/'. Skip that + * slash, and continue until no more slashes. + */ + do { + len++; + } while (unlikely(name[len] == '/')); + if (!name[len]) goto last_component; + name += len; err = walk_component(nd, &next, &this, type, LOOKUP_FOLLOW); if (err < 0) -- cgit v1.1 From ae942ae71934fddd0639160c24f6efa703d5784e Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Fri, 2 Mar 2012 19:40:57 -0800 Subject: vfs: export full_name_hash() function to modules Commit 5707c87f "vfs: uninline full_name_hash()" broke the modular build, because it needs exporting now that it isn't inlined any more. Reported-by: Tetsuo Handa Signed-off-by: Linus Torvalds --- fs/namei.c | 1 + 1 file changed, 1 insertion(+) (limited to 'fs/namei.c') diff --git a/fs/namei.c b/fs/namei.c index 71807dc..e2ba628 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -1381,6 +1381,7 @@ unsigned int full_name_hash(const unsigned char *name, unsigned int len) hash = partial_name_hash(*name++, hash); return end_name_hash(hash); } +EXPORT_SYMBOL(full_name_hash); /* * We know there's a real path component here of at least -- cgit v1.1