fs: simplify iget & friends

Merge get_new_inode/get_new_inode_fast into iget5_locked/iget_locked
as those were the only callers.  Remove the internal ifind/ifind_fast
helpers - ifind_fast only had a single caller, and ifind had two
callers wanting it to do different things.  Also clean up the comments
in this area to focus on information important to a developer trying
to use it, instead of overloading them with implementation details.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 83 insertions, 179 deletions

diff --git a/fs/inode.c b/fs/inode.c
index f9ee4928358f..05a1f75ae791 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -931,20 +931,42 @@ void unlock_new_inode(struct inode *inode)
 }
 EXPORT_SYMBOL(unlock_new_inode);
 
-/*
- * This is called without the inode hash lock held.. Be careful.
+/**
+ * iget5_locked - obtain an inode from a mounted file system
+ * @sb:         super block of file system
+ * @hashval:    hash value (usually inode number) to get
+ * @test:       callback used for comparisons between inodes
+ * @set:        callback used to initialize a new struct inode
+ * @data:       opaque data pointer to pass to @test and @set
+ *
+ * Search for the inode specified by @hashval and @data in the inode cache,
+ * and if present it is return it with an increased reference count. This is
+ * a generalized version of iget_locked() for file systems where the inode
+ * number is not sufficient for unique identification of an inode.
+ *
+ * If the inode is not in cache, allocate a new inode and return it locked,
+ * hashed, and with the I_NEW flag set. The file system gets to fill it in
+ * before unlocking it via unlock_new_inode().
  *
- * We no longer cache the sb_flags in i_flags - see fs.h
- *      -- rmk@arm.uk.linux.org
+ * Note both @test and @set are called with the inode_hash_lock held, so can't
+ * sleep.
  */
-static struct inode *get_new_inode(struct super_block *sb,
-                                struct hlist_head *head,
-                                int (*test)(struct inode *, void *),
-                                int (*set)(struct inode *, void *),
-                                void *data)
+struct inode *iget5_locked(struct super_block *sb, unsigned long hashval,
+                int (*test)(struct inode *, void *),
+                int (*set)(struct inode *, void *), void *data)
 {
+        struct hlist_head *head = inode_hashtable + hash(sb, hashval);
         struct inode *inode;
 
+        spin_lock(&inode_hash_lock);
+        inode = find_inode(sb, head, test, data);
+        spin_unlock(&inode_hash_lock);
+
+        if (inode) {
+                wait_on_inode(inode);
+                return inode;
+        }
+
         inode = alloc_inode(sb);
         if (inode) {
                 struct inode *old;
@@ -986,16 +1008,34 @@ set_failed:
         destroy_inode(inode);
         return NULL;
 }
+EXPORT_SYMBOL(iget5_locked);
 
-/*
- * get_new_inode_fast is the fast path version of get_new_inode, see the
- * comment at iget_locked for details.
+/**
+ * iget_locked - obtain an inode from a mounted file system
+ * @sb:         super block of file system
+ * @ino:        inode number to get
+ *
+ * Search for the inode specified by @ino in the inode cache and if present
+ * return it with an increased reference count. This is for file systems
+ * where the inode number is sufficient for unique identification of an inode.
+ *
+ * If the inode is not in cache, allocate a new inode and return it locked,
+ * hashed, and with the I_NEW flag set.  The file system gets to fill it in
+ * before unlocking it via unlock_new_inode().
  */
-static struct inode *get_new_inode_fast(struct super_block *sb,
-                                struct hlist_head *head, unsigned long ino)
+struct inode *iget_locked(struct super_block *sb, unsigned long ino)
 {
+        struct hlist_head *head = inode_hashtable + hash(sb, ino);
         struct inode *inode;
 
+        spin_lock(&inode_hash_lock);
+        inode = find_inode_fast(sb, head, ino);
+        spin_unlock(&inode_hash_lock);
+        if (inode) {
+                wait_on_inode(inode);
+                return inode;
+        }
+
         inode = alloc_inode(sb);
         if (inode) {
                 struct inode *old;
@@ -1030,6 +1070,7 @@ static struct inode *get_new_inode_fast(struct super_block *sb,
         }
         return inode;
 }
+EXPORT_SYMBOL(iget_locked);
 
 /*
  * search the inode cache for a matching inode number.
@@ -1113,100 +1154,32 @@ struct inode *igrab(struct inode *inode)
 EXPORT_SYMBOL(igrab);
 
 /**
- * ifind - internal function, you want ilookup5() or iget5().
+ * ilookup5_nowait - search for an inode in the inode cache
  * @sb:         super block of file system to search
- * @head:       the head of the list to search
+ * @hashval:    hash value (usually inode number) to search for
  * @test:       callback used for comparisons between inodes
  * @data:       opaque data pointer to pass to @test
- * @wait:       if true wait for the inode to be unlocked, if false do not
- *
- * ifind() searches for the inode specified by @data in the inode
- * cache. This is a generalized version of ifind_fast() for file systems where
- * the inode number is not sufficient for unique identification of an inode.
  *
+ * Search for the inode specified by @hashval and @data in the inode cache.
  * If the inode is in the cache, the inode is returned with an incremented
  * reference count.
  *
- * Otherwise NULL is returned.
+ * Note: I_NEW is not waited upon so you have to be very careful what you do
+ * with the returned inode.  You probably should be using ilookup5() instead.
  *
- * Note, @test is called with the inode_hash_lock held, so can't sleep.
+ * Note: @test is called with the inode_hash_lock held, so can't sleep.
  */
-static struct inode *ifind(struct super_block *sb,
-                struct hlist_head *head, int (*test)(struct inode *, void *),
-                void *data, const int wait)
+struct inode *ilookup5_nowait(struct super_block *sb, unsigned long hashval,
+                int (*test)(struct inode *, void *), void *data)
 {
+        struct hlist_head *head = inode_hashtable + hash(sb, hashval);
         struct inode *inode;
 
         spin_lock(&inode_hash_lock);
         inode = find_inode(sb, head, test, data);
-        if (inode) {
-                spin_unlock(&inode_hash_lock);
-                if (likely(wait))
-                        wait_on_inode(inode);
-                return inode;
-        }
-        spin_unlock(&inode_hash_lock);
-        return NULL;
-}
-
-/**
- * ifind_fast - internal function, you want ilookup() or iget().
- * @sb:         super block of file system to search
- * @head:       head of the list to search
- * @ino:        inode number to search for
- *
- * ifind_fast() searches for the inode @ino in the inode cache. This is for
- * file systems where the inode number is sufficient for unique identification
- * of an inode.
- *
- * If the inode is in the cache, the inode is returned with an incremented
- * reference count.
- *
- * Otherwise NULL is returned.
- */
-static struct inode *ifind_fast(struct super_block *sb,
-                struct hlist_head *head, unsigned long ino)
-{
-        struct inode *inode;
-
-        spin_lock(&inode_hash_lock);
-        inode = find_inode_fast(sb, head, ino);
-        if (inode) {
-                spin_unlock(&inode_hash_lock);
-                wait_on_inode(inode);
-                return inode;
-        }
         spin_unlock(&inode_hash_lock);
-        return NULL;
-}
-
-/**
- * ilookup5_nowait - search for an inode in the inode cache
- * @sb:         super block of file system to search
- * @hashval:    hash value (usually inode number) to search for
- * @test:       callback used for comparisons between inodes
- * @data:       opaque data pointer to pass to @test
- *
- * ilookup5() uses ifind() to search for the inode specified by @hashval and
- * @data in the inode cache. This is a generalized version of ilookup() for
- * file systems where the inode number is not sufficient for unique
- * identification of an inode.
- *
- * If the inode is in the cache, the inode is returned with an incremented
- * reference count.  Note, the inode lock is not waited upon so you have to be
- * very careful what you do with the returned inode.  You probably should be
- * using ilookup5() instead.
- *
- * Otherwise NULL is returned.
- *
- * Note, @test is called with the inode_hash_lock held, so can't sleep.
- */
-struct inode *ilookup5_nowait(struct super_block *sb, unsigned long hashval,
-                int (*test)(struct inode *, void *), void *data)
-{
-        struct hlist_head *head = inode_hashtable + hash(sb, hashval);
 
-        return ifind(sb, head, test, data, 0);
+        return inode;
 }
 EXPORT_SYMBOL(ilookup5_nowait);
 
@@ -1217,24 +1190,24 @@ EXPORT_SYMBOL(ilookup5_nowait);
  * @test:       callback used for comparisons between inodes
  * @data:       opaque data pointer to pass to @test
  *
- * ilookup5() uses ifind() to search for the inode specified by @hashval and
- * @data in the inode cache. This is a generalized version of ilookup() for
- * file systems where the inode number is not sufficient for unique
- * identification of an inode.
- *
- * If the inode is in the cache, the inode lock is waited upon and the inode is
+ * Search for the inode specified by @hashval and @data in the inode cache,
+ * and if the inode is in the cache, return the inode with an incremented
+ * reference count.  Waits on I_NEW before returning the inode.
  * returned with an incremented reference count.
  *
- * Otherwise NULL is returned.
+ * This is a generalized version of ilookup() for file systems where the
+ * inode number is not sufficient for unique identification of an inode.
  *
- * Note, @test is called with the inode_hash_lock held, so can't sleep.
+ * Note: @test is called with the inode_hash_lock held, so can't sleep.
  */
 struct inode *ilookup5(struct super_block *sb, unsigned long hashval,
                 int (*test)(struct inode *, void *), void *data)
 {
-        struct hlist_head *head = inode_hashtable + hash(sb, hashval);
+        struct inode *inode = ilookup5_nowait(sb, hashval, test, data);
 
-        return ifind(sb, head, test, data, 1);
+        if (inode)
+                wait_on_inode(inode);
+        return inode;
 }
 EXPORT_SYMBOL(ilookup5);
 
@@ -1243,92 +1216,23 @@ EXPORT_SYMBOL(ilookup5);
  * @sb:         super block of file system to search
  * @ino:        inode number to search for
  *
- * ilookup() uses ifind_fast() to search for the inode @ino in the inode cache.
- * This is for file systems where the inode number is sufficient for unique
- * identification of an inode.
- *
- * If the inode is in the cache, the inode is returned with an incremented
- * reference count.
- *
- * Otherwise NULL is returned.
+ * Search for the inode @ino in the inode cache, and if the inode is in the
+ * cache, the inode is returned with an incremented reference count.
  */
 struct inode *ilookup(struct super_block *sb, unsigned long ino)
 {
         struct hlist_head *head = inode_hashtable + hash(sb, ino);
-
-        return ifind_fast(sb, head, ino);
-}
-EXPORT_SYMBOL(ilookup);
-
-/**
- * iget5_locked - obtain an inode from a mounted file system
- * @sb:         super block of file system
- * @hashval:    hash value (usually inode number) to get
- * @test:       callback used for comparisons between inodes
- * @set:        callback used to initialize a new struct inode
- * @data:       opaque data pointer to pass to @test and @set
- *
- * iget5_locked() uses ifind() to search for the inode specified by @hashval
- * and @data in the inode cache and if present it is returned with an increased
- * reference count. This is a generalized version of iget_locked() for file
- * systems where the inode number is not sufficient for unique identification
- * of an inode.
- *
- * If the inode is not in cache, get_new_inode() is called to allocate a new
- * inode and this is returned locked, hashed, and with the I_NEW flag set. The
- * file system gets to fill it in before unlocking it via unlock_new_inode().
- *
- * Note both @test and @set are called with the inode_hash_lock held, so can't
- * sleep.
- */
-struct inode *iget5_locked(struct super_block *sb, unsigned long hashval,
-                int (*test)(struct inode *, void *),
-                int (*set)(struct inode *, void *), void *data)
-{
-        struct hlist_head *head = inode_hashtable + hash(sb, hashval);
         struct inode *inode;
 
-        inode = ifind(sb, head, test, data, 1);
-        if (inode)
-                return inode;
-        /*
-         * get_new_inode() will do the right thing, re-trying the search
-         * in case it had to block at any point.
-         */
-        return get_new_inode(sb, head, test, set, data);
-}
-EXPORT_SYMBOL(iget5_locked);
-
-/**
- * iget_locked - obtain an inode from a mounted file system
- * @sb:         super block of file system
- * @ino:        inode number to get
- *
- * iget_locked() uses ifind_fast() to search for the inode specified by @ino in
- * the inode cache and if present it is returned with an increased reference
- * count. This is for file systems where the inode number is sufficient for
- * unique identification of an inode.
- *
- * If the inode is not in cache, get_new_inode_fast() is called to allocate a
- * new inode and this is returned locked, hashed, and with the I_NEW flag set.
- * The file system gets to fill it in before unlocking it via
- * unlock_new_inode().
- */
-struct inode *iget_locked(struct super_block *sb, unsigned long ino)
-{
-        struct hlist_head *head = inode_hashtable + hash(sb, ino);
-        struct inode *inode;
+        spin_lock(&inode_hash_lock);
+        inode = find_inode_fast(sb, head, ino);
+        spin_unlock(&inode_hash_lock);
 
-        inode = ifind_fast(sb, head, ino);
         if (inode)
-                return inode;
-        /*
-         * get_new_inode_fast() will do the right thing, re-trying the search
-         * in case it had to block at any point.
-         */
-        return get_new_inode_fast(sb, head, ino);
+                wait_on_inode(inode);
+        return inode;
 }
-EXPORT_SYMBOL(iget_locked);
+EXPORT_SYMBOL(ilookup);
 
 int insert_inode_locked(struct inode *inode)
 {