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Subject[PATCH 9/8] 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>

Index: xfs/fs/inode.c
===================================================================
--- xfs.orig/fs/inode.c 2011-03-23 12:52:49.898877203 +0100
+++ xfs/fs/inode.c 2011-03-23 12:52:57.066879923 +0100
@@ -930,20 +930,42 @@ void unlock_new_inode(struct inode *inod
}
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
*
- * We no longer cache the sb_flags in i_flags - see fs.h
- * -- rmk@arm.uk.linux.org
+ * 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().
+ *
+ * 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;
@@ -985,16 +1007,34 @@ 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;
@@ -1029,6 +1069,7 @@ static struct inode *get_new_inode_fast(
}
return inode;
}
+EXPORT_SYMBOL(iget_locked);

/*
* search the inode cache for a matching inode number.
@@ -1112,100 +1153,32 @@ 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);

@@ -1216,24 +1189,24 @@ 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);

@@ -1242,92 +1215,23 @@ 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)
{

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