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From: Jan Harkes <jaharkes@cs.cmu.edu>
To: torvalds@transmeta.com
Subject: [PATCH] iget_locked [1/6]
Date: Fri, 10 May 2002 12:07:19 -0400
Cc: linux-kernel@vger.kernel.org, Alexander Viro <viro@math.psu.edu>,
trond.myklebust@fys.uio.no, reiserfs-dev@namesys.com
Hi Linus,
Here is a series of 6 patches that started off as fixing a race in
iget4, but ended up as a merge of the XFS icreate functionality, removal
of the 'reiserfs specific hack' and reduces the VFS dependency on i_ino.
It has seen some discussion on linux-fsdevel.
It removes iget4 and the read_inode2 callback, adds an argument to the
interface of insert_inode_hash and introduces new functions iget_locked,
iget5_locked and unlock_new_inode.
The main difference between iget_locked and iget is that iget_locked
returns a locked inode and leaves it up the the filesystem to deal with
the final initialization of the inode. Once all filesystems are
converted to use iget_locked, the read_inode callback can be removed as
well.
Jan
Patches start off against 2.5.15.
Fix a race in iget4. The fs specific data that is used to find an inode
should be initialized while still holding the inode lock.
It adds a 'set' callback function that should be a non-blocking FS
provided function that initializes the private parts of the inode so
that the 'test' callback function can correctly match new inodes.
Touches all filesystems that use iget4 (Coda/NFS/ReiserFS).
======
diff -urN orig/fs/coda/cnode.c iget_locked-1/fs/coda/cnode.c
--- orig/fs/coda/cnode.c Wed Apr 24 21:39:46 2002
+++ iget_locked-1/fs/coda/cnode.c Fri May 10 10:32:03 2002
@@ -25,11 +25,6 @@
return 1;
}
-static int coda_inocmp(struct inode *inode, unsigned long ino, void *opaque)
-{
- return (coda_fideq((ViceFid *)opaque, &(ITOC(inode)->c_fid)));
-}
-
static struct inode_operations coda_symlink_inode_operations = {
readlink: page_readlink,
follow_link: page_follow_link,
@@ -55,27 +50,35 @@
init_special_inode(inode, inode->i_mode, attr->va_rdev);
}
+static int coda_test_inode(struct inode *inode, void *data)
+{
+ ViceFid *fid = (ViceFid *)data;
+ return coda_fideq(&(ITOC(inode)->c_fid), fid);
+}
+
+static int coda_set_inode(struct inode *inode, void *data)
+{
+ ViceFid *fid = (ViceFid *)data;
+ ITOC(inode)->c_fid = *fid;
+ return 0;
+}
+
+static int coda_fail_inode(struct inode *inode, void *data)
+{
+ return -1;
+}
+
struct inode * coda_iget(struct super_block * sb, ViceFid * fid,
struct coda_vattr * attr)
{
struct inode *inode;
- struct coda_inode_info *cii;
ino_t ino = coda_f2i(fid);
- inode = iget4(sb, ino, coda_inocmp, fid);
+ inode = iget4(sb, ino, coda_test_inode, coda_set_inode, fid);
if (!inode)
return ERR_PTR(-ENOMEM);
- /* check if the inode is already initialized */
- cii = ITOC(inode);
- if (coda_isnullfid(&cii->c_fid))
- /* new, empty inode found... initializing */
- cii->c_fid = *fid;
-
- /* we shouldnt see inode collisions anymore */
- if (!coda_fideq(fid, &cii->c_fid)) BUG();
-
/* always replace the attributes, type might have changed */
coda_fill_inode(inode, attr);
return inode;
@@ -131,7 +134,6 @@
{
ino_t nr;
struct inode *inode;
- struct coda_inode_info *cii;
if ( !sb ) {
printk("coda_fid_to_inode: no sb!\n");
@@ -139,43 +141,29 @@
}
nr = coda_f2i(fid);
- inode = iget4(sb, nr, coda_inocmp, fid);
+ inode = iget4(sb, nr, coda_test_inode, coda_fail_inode, fid);
if ( !inode ) {
printk("coda_fid_to_inode: null from iget, sb %p, nr %ld.\n",
sb, (long)nr);
return NULL;
}
- cii = ITOC(inode);
-
- /* The inode could already be purged due to memory pressure */
- if (coda_isnullfid(&cii->c_fid)) {
- inode->i_nlink = 0;
- iput(inode);
- return NULL;
- }
-
- /* we shouldn't see inode collisions anymore */
- if ( !coda_fideq(fid, &cii->c_fid) ) BUG();
-
- return inode;
+ return inode;
}
/* the CONTROL inode is made without asking attributes from Venus */
int coda_cnode_makectl(struct inode **inode, struct super_block *sb)
{
- int error = 0;
+ int error = -ENOMEM;
+
+ *inode = iget(sb, CTL_INO);
+ if ( *inode ) {
+ (*inode)->i_op = &coda_ioctl_inode_operations;
+ (*inode)->i_fop = &coda_ioctl_operations;
+ (*inode)->i_mode = 0444;
+ error = 0;
+ }
- *inode = iget(sb, CTL_INO);
- if ( *inode ) {
- (*inode)->i_op = &coda_ioctl_inode_operations;
- (*inode)->i_fop = &coda_ioctl_operations;
- (*inode)->i_mode = 0444;
- error = 0;
- } else {
- error = -ENOMEM;
- }
-
- return error;
+ return error;
}
diff -urN orig/fs/inode.c iget_locked-1/fs/inode.c
--- orig/fs/inode.c Wed May 1 00:27:35 2002
+++ iget_locked-1/fs/inode.c Fri May 10 10:32:03 2002
@@ -452,7 +452,7 @@
* by hand after calling find_inode now! This simplifies iunique and won't
* add any additional branch in the common code.
*/
-static struct inode * find_inode(struct super_block * sb, unsigned long ino, struct list_head *head, find_inode_t find_actor, void *opaque)
+static struct inode * find_inode(struct super_block * sb, unsigned long ino, struct list_head *head, int (*test)(struct inode *, void *), void *data)
{
struct list_head *tmp;
struct inode * inode;
@@ -468,7 +468,7 @@
continue;
if (inode->i_sb != sb)
continue;
- if (find_actor && !find_actor(inode, ino, opaque))
+ if (test && !test(inode, data))
continue;
break;
}
@@ -507,9 +507,10 @@
* We no longer cache the sb_flags in i_flags - see fs.h
* -- rmk@arm.uk.linux.org
*/
-static struct inode * get_new_inode(struct super_block *sb, unsigned long ino, struct list_head *head, find_inode_t find_actor, void *opaque)
+static struct inode * get_new_inode(struct super_block *sb, unsigned long ino, struct list_head *head, int (*test)(struct inode *, void *), int (*set)(struct inode *, void *), void *data)
{
struct inode * inode;
+ int err = 0;
inode = alloc_inode(sb);
if (inode) {
@@ -517,22 +518,31 @@
spin_lock(&inode_lock);
/* We released the lock, so.. */
- old = find_inode(sb, ino, head, find_actor, opaque);
+ old = find_inode(sb, ino, head, test, data);
if (!old) {
- inodes_stat.nr_inodes++;
- list_add(&inode->i_list, &inode_in_use);
- list_add(&inode->i_hash, head);
inode->i_ino = ino;
- inode->i_state = I_LOCK;
+ if (set)
+ err = set(inode, data);
+ if (!err) {
+ inodes_stat.nr_inodes++;
+ list_add(&inode->i_list, &inode_in_use);
+ list_add(&inode->i_hash, head);
+ inode->i_state = I_LOCK;
+ }
spin_unlock(&inode_lock);
+ if (err) {
+ destroy_inode(inode);
+ return NULL;
+ }
+
/* reiserfs specific hack right here. We don't
** want this to last, and are looking for VFS changes
** that will allow us to get rid of it.
** -- mason@suse.com
*/
if (sb->s_op->read_inode2) {
- sb->s_op->read_inode2(inode, opaque) ;
+ sb->s_op->read_inode2(inode, data) ;
} else {
sb->s_op->read_inode(inode);
}
@@ -628,13 +638,13 @@
}
-struct inode *iget4(struct super_block *sb, unsigned long ino, find_inode_t find_actor, void *opaque)
+struct inode *iget4(struct super_block *sb, unsigned long ino, int (*test)(struct inode *, void *), int (*set)(struct inode *, void *), void *data)
{
struct list_head * head = inode_hashtable + hash(sb,ino);
struct inode * inode;
spin_lock(&inode_lock);
- inode = find_inode(sb, ino, head, find_actor, opaque);
+ inode = find_inode(sb, ino, head, test, data);
if (inode) {
__iget(inode);
spin_unlock(&inode_lock);
@@ -647,7 +657,7 @@
* 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, ino, head, find_actor, opaque);
+ return get_new_inode(sb, ino, head, test, set, data);
}
/**
diff -urN orig/fs/nfs/inode.c iget_locked-1/fs/nfs/inode.c
--- orig/fs/nfs/inode.c Wed May 1 00:27:35 2002
+++ iget_locked-1/fs/nfs/inode.c Fri May 10 10:32:03 2002
@@ -592,7 +592,7 @@
* i_ino.
*/
static int
-nfs_find_actor(struct inode *inode, unsigned long ino, void *opaque)
+nfs_find_actor(struct inode *inode, void *opaque)
{
struct nfs_find_desc *desc = (struct nfs_find_desc *)opaque;
struct nfs_fh *fh = desc->fh;
@@ -610,6 +610,18 @@
return 1;
}
+static int
+nfs_init_locked(struct inode *inode, void *opaque)
+{
+ struct nfs_find_desc *desc = (struct nfs_find_desc *)opaque;
+ struct nfs_fh *fh = desc->fh;
+ struct nfs_fattr *fattr = desc->fattr;
+
+ NFS_FILEID(inode) = fattr->fileid;
+ memcpy(NFS_FH(inode), fh, sizeof(struct nfs_fh));
+ return 0;
+}
+
/*
* This is our own version of iget that looks up inodes by file handle
* instead of inode number. We use this technique instead of using
@@ -652,7 +664,7 @@
ino = nfs_fattr_to_ino_t(fattr);
- if (!(inode = iget4(sb, ino, nfs_find_actor, &desc)))
+ if (!(inode = iget4(sb, ino, nfs_find_actor, nfs_init_locked, &desc)))
goto out_no_inode;
if (NFS_NEW(inode)) {
@@ -662,8 +674,6 @@
/* We can't support UPDATE_ATIME(), since the server will reset it */
NFS_FLAGS(inode) &= ~NFS_INO_NEW;
- NFS_FILEID(inode) = fattr->fileid;
- memcpy(NFS_FH(inode), fh, sizeof(struct nfs_fh));
inode->i_flags |= S_NOATIME;
inode->i_mode = fattr->mode;
/* Why so? Because we want revalidate for devices/FIFOs, and
diff -urN orig/fs/reiserfs/inode.c iget_locked-1/fs/reiserfs/inode.c
--- orig/fs/reiserfs/inode.c Fri May 10 10:30:07 2002
+++ iget_locked-1/fs/reiserfs/inode.c Fri May 10 10:32:03 2002
@@ -1138,6 +1138,13 @@
// evolved as the prototype did
//
+int reiserfs_init_locked_inode (struct inode * inode, void *p)
+{
+ struct reiserfs_iget4_args *args = (struct reiserfs_iget4_args *)p ;
+ INODE_PKEY(inode)->k_dir_id = cpu_to_le32(args->objectid);
+ return 0;
+}
+
/* looks for stat data in the tree, and fills up the fields of in-core
inode stat data fields */
void reiserfs_read_inode2 (struct inode * inode, void *p)
@@ -1213,7 +1220,6 @@
* reiserfs_find_actor() - "find actor" reiserfs supplies to iget4().
*
* @inode: inode from hash table to check
- * @inode_no: inode number we are looking for
* @opaque: "cookie" passed to iget4(). This is &reiserfs_iget4_args.
*
* This function is called by iget4() to distinguish reiserfs inodes
@@ -1222,8 +1228,7 @@
* inode numbers (objectids) are distinguished by parent directory ids.
*
*/
-static int reiserfs_find_actor( struct inode *inode,
- unsigned long inode_no, void *opaque )
+int reiserfs_find_actor( struct inode *inode, void *opaque )
{
struct reiserfs_iget4_args *args;
@@ -1239,7 +1244,7 @@
args.objectid = key->on_disk_key.k_dir_id ;
inode = iget4 (s, key->on_disk_key.k_objectid,
- reiserfs_find_actor, (void *)(&args));
+ reiserfs_find_actor, reiserfs_init_locked_inode, (void *)(&args));
if (!inode)
return ERR_PTR(-ENOMEM) ;
diff -urN orig/fs/reiserfs/super.c iget_locked-1/fs/reiserfs/super.c
--- orig/fs/reiserfs/super.c Fri May 10 10:30:07 2002
+++ iget_locked-1/fs/reiserfs/super.c Fri May 10 10:32:03 2002
@@ -1070,7 +1070,7 @@
s->s_flags |= MS_RDONLY ;
}
args.objectid = REISERFS_ROOT_PARENT_OBJECTID ;
- root_inode = iget4 (s, REISERFS_ROOT_OBJECTID, 0, (void *)(&args));
+ root_inode = iget4 (s, REISERFS_ROOT_OBJECTID, reiserfs_find_actor, reiserfs_init_locked_inode, (void *)(&args));
if (!root_inode) {
printk ("reiserfs_fill_super: get root inode failed\n");
goto error;
diff -urN orig/include/linux/fs.h iget_locked-1/include/linux/fs.h
--- orig/include/linux/fs.h Sat May 4 19:25:53 2002
+++ iget_locked-1/include/linux/fs.h Fri May 10 10:32:04 2002
@@ -1240,11 +1240,10 @@
extern struct inode * igrab(struct inode *);
extern ino_t iunique(struct super_block *, ino_t);
-typedef int (*find_inode_t)(struct inode *, unsigned long, void *);
-extern struct inode * iget4(struct super_block *, unsigned long, find_inode_t, void *);
+extern struct inode * iget4(struct super_block *, unsigned long, int (*test)(struct inode *, void *), int (*set)(struct inode *, void *), void *);
static inline struct inode *iget(struct super_block *sb, unsigned long ino)
{
- return iget4(sb, ino, NULL, NULL);
+ return iget4(sb, ino, NULL, NULL, NULL);
}
extern void __iget(struct inode * inode);
diff -urN orig/include/linux/reiserfs_fs.h iget_locked-1/include/linux/reiserfs_fs.h
--- orig/include/linux/reiserfs_fs.h Fri May 10 10:30:08 2002
+++ iget_locked-1/include/linux/reiserfs_fs.h Fri May 10 10:32:04 2002
@@ -1820,6 +1820,8 @@
void reiserfs_read_inode (struct inode * inode) ;
void reiserfs_read_inode2(struct inode * inode, void *p) ;
+int reiserfs_find_actor(struct inode * inode, void *p) ;
+int reiserfs_init_locked_inode(struct inode * inode, void *p) ;
void reiserfs_delete_inode (struct inode * inode);
void reiserfs_write_inode (struct inode * inode, int) ;
struct dentry *reiserfs_get_dentry(struct super_block *, void *) ;
-
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