| From: |
| Christoph Hellwig <hch@lst.de> |
| To: |
| torvalds@transmeta.com |
| Subject: |
| [PATCH] libfs |
| Date: |
| Sat, 5 Apr 2003 22:58:46 +0200 |
| Cc: |
| linux-kernel@vger.kernel.org |
Al added fs/libfs.c for common library routines used by filesysems
a while ago, but we have a lot more such library funcions, say
fs/exportfs/ or stuff scribbled all over the core VFS files.
This patch adds a fs/libfs/ dir instead, starting with simple.c
(simple, ramfs-based filesystems), symlink.c (pagecache-based
symlink code) and export.c (Neil's common export helpers). In
the long term I think it's a good idea too, to have the prototypes
for all this (and whatever we more over) to <linux/libfs.h> so
it's clear they are only intended for filesystem driver, and we
don't get into situations like those people trying to use
do_generic_file_read from inkernel servers like in 2.4.
(I've send this as combined BK/plain patch because the BK patch
can track the renames, but the plain patch works fine aswell)
You can import this changeset into BK by piping this whole message to:
'| bk receive [path to repository]' or apply the patch as usual.
===================================================================
ChangeSet@1.1034, 2003-04-05 21:08:39-05:00, hch@sb.bsdonline.org
libfs cleanup
b/fs/Makefile | 5
b/fs/libfs/Makefile | 3
b/fs/libfs/export.c | 536 +++++++++++++++++++++++++++++++++++++++++++++++++++
b/fs/libfs/simple.c | 334 +++++++++++++++++++++++++++++++
b/fs/libfs/symlink.c | 100 +++++++++
b/fs/namei.c | 101 ---------
fs/exportfs/expfs.c | 536 ---------------------------------------------------
fs/libfs.c | 334 -------------------------------
8 files changed, 976 insertions(+), 973 deletions(-)
diff -Nru a/fs/Makefile b/fs/Makefile
--- a/fs/Makefile Sat Apr 5 21:29:54 2003
+++ b/fs/Makefile Sat Apr 5 21:29:54 2003
@@ -5,11 +5,11 @@
# Rewritten to use lists instead of if-statements.
#
-obj-y := open.o read_write.o file_table.o buffer.o \
+obj-y := libfs/ open.o read_write.o file_table.o buffer.o \
bio.o super.o block_dev.o char_dev.o stat.o exec.o pipe.o \
namei.o fcntl.o ioctl.o readdir.o select.o fifo.o locks.o \
dcache.o inode.o attr.o bad_inode.o file.o dnotify.o \
- filesystems.o namespace.o seq_file.o xattr.o libfs.o \
+ filesystems.o namespace.o seq_file.o xattr.o \
fs-writeback.o mpage.o direct-io.o aio.o eventpoll.o
obj-$(CONFIG_COMPAT) += compat.o
@@ -66,7 +66,6 @@
obj-$(CONFIG_HFS_FS) += hfs/
obj-$(CONFIG_VXFS_FS) += freevxfs/
obj-$(CONFIG_NFS_FS) += nfs/
-obj-$(CONFIG_EXPORTFS) += exportfs/
obj-$(CONFIG_NFSD) += nfsd/
obj-$(CONFIG_LOCKD) += lockd/
obj-$(CONFIG_NLS) += nls/
diff -Nru a/fs/exportfs/expfs.c b/fs/exportfs/expfs.c
--- a/fs/exportfs/expfs.c Sat Apr 5 21:29:54 2003
+++ /dev/null Wed Dec 31 16:00:00 1969
@@ -1,536 +0,0 @@
-
-#include <linux/fs.h>
-#include <linux/module.h>
-#include <linux/smp_lock.h>
-#include <linux/namei.h>
-
-struct export_operations export_op_default;
-
-#define CALL(ops,fun) ((ops->fun)?(ops->fun):export_op_default.fun)
-
-#define dprintk(fmt, args...) do{}while(0)
-
-/**
- * find_exported_dentry - helper routine to implement export_operations->decode_fh
- * @sb: The &super_block identifying the filesystem
- * @obj: An opaque identifier of the object to be found - passed to
- * get_inode
- * @parent: An optional opqaue identifier of the parent of the object.
- * @acceptable: A function used to test possible &dentries to see if they are
- * acceptable
- * @context: A parameter to @acceptable so that it knows on what basis to
- * judge.
- *
- * find_exported_dentry is the central helper routine to enable file systems
- * to provide the decode_fh() export_operation. It's main task is to take
- * an &inode, find or create an appropriate &dentry structure, and possibly
- * splice this into the dcache in the correct place.
- *
- * The decode_fh() operation provided by the filesystem should call
- * find_exported_dentry() with the same parameters that it received except
- * that instead of the file handle fragment, pointers to opaque identifiers
- * for the object and optionally its parent are passed. The default decode_fh
- * routine passes one pointer to the start of the filehandle fragment, and
- * one 8 bytes into the fragment. It is expected that most filesystems will
- * take this approach, though the offset to the parent identifier may well be
- * different.
- *
- * find_exported_dentry() will call get_dentry to get an dentry pointer from
- * the file system. If any &dentry in the d_alias list is acceptable, it will
- * be returned. Otherwise find_exported_dentry() will attempt to splice a new
- * &dentry into the dcache using get_name() and get_parent() to find the
- * appropriate place.
- */
-
-struct dentry *
-find_exported_dentry(struct super_block *sb, void *obj, void *parent,
- int (*acceptable)(void *context, struct dentry *de),
- void *context)
-{
- struct dentry *result = NULL;
- struct dentry *target_dir;
- int err;
- struct export_operations *nops = sb->s_export_op;
- struct list_head *le, *head;
- struct dentry *toput = NULL;
- int noprogress;
-
-
- /*
- * Attempt to find the inode.
- */
- result = CALL(sb->s_export_op,get_dentry)(sb,obj);
- err = -ESTALE;
- if (result == NULL)
- goto err_out;
- if (IS_ERR(result)) {
- err = PTR_ERR(result);
- goto err_out;
- }
- if (S_ISDIR(result->d_inode->i_mode) &&
- (result->d_flags & DCACHE_DISCONNECTED)) {
- /* it is an unconnected directory, we must connect it */
- ;
- } else {
- if (acceptable(context, result))
- return result;
- if (S_ISDIR(result->d_inode->i_mode)) {
- /* there is no other dentry, so fail */
- goto err_result;
- }
- /* try any other aliases */
- spin_lock(&dcache_lock);
- head = &result->d_inode->i_dentry;
- list_for_each(le, head) {
- struct dentry *dentry = list_entry(le, struct dentry, d_alias);
- dget_locked(dentry);
- spin_unlock(&dcache_lock);
- if (toput)
- dput(toput);
- toput = NULL;
- if (dentry != result &&
- acceptable(context, dentry)) {
- dput(result);
- dentry->d_vfs_flags |= DCACHE_REFERENCED;
- return dentry;
- }
- spin_lock(&dcache_lock);
- toput = dentry;
- }
- spin_unlock(&dcache_lock);
- if (toput)
- dput(toput);
- }
-
- /* It's a directory, or we are required to confirm the file's
- * location in the tree based on the parent information
- */
- dprintk("find_exported_dentry: need to look harder for %s/%d\n",sb->s_id,*(int*)obj);
- if (S_ISDIR(result->d_inode->i_mode))
- target_dir = dget(result);
- else {
- if (parent == NULL)
- goto err_result;
-
- target_dir = CALL(sb->s_export_op,get_dentry)(sb,parent);
- if (IS_ERR(target_dir))
- err = PTR_ERR(target_dir);
- if (target_dir == NULL || IS_ERR(target_dir))
- goto err_result;
- }
- /*
- * Now we need to make sure that target_dir is properly connected.
- * It may already be, as the flag isn't always updated when connection
- * happens.
- * So, we walk up parent links until we find a connected directory,
- * or we run out of directories. Then we find the parent, find
- * the name of the child in that parent, and do a lookup.
- * This should connect the child into the parent
- * We then repeat.
- */
-
- /* it is possible that a confused file system might not let us complete
- * the path to the root. For example, if get_parent returns a directory
- * in which we cannot find a name for the child. While this implies a
- * very sick filesystem we don't want it to cause knfsd to spin. Hence
- * the noprogress counter. If we go through the loop 10 times (2 is
- * probably enough) without getting anywhere, we just give up
- */
- lock_kernel();
- noprogress= 0;
- while (target_dir->d_flags & DCACHE_DISCONNECTED && noprogress++ < 10) {
- struct dentry *pd = target_dir;
-
- dget(pd);
- spin_lock(&pd->d_lock);
- while (!IS_ROOT(pd) &&
- (pd->d_parent->d_flags&DCACHE_DISCONNECTED)) {
- struct dentry *parent = pd->d_parent;
-
- dget(parent);
- spin_unlock(&pd->d_lock);
- dput(pd);
- pd = parent;
- spin_lock(&pd->d_lock);
- }
- spin_unlock(&pd->d_lock);
-
- if (!IS_ROOT(pd)) {
- /* must have found a connected parent - great */
- pd->d_flags &= ~DCACHE_DISCONNECTED;
- noprogress = 0;
- } else if (pd == sb->s_root) {
- printk(KERN_ERR "export: Eeek filesystem root is not connected, impossible\n");
- pd->d_flags &= ~DCACHE_DISCONNECTED;
- noprogress = 0;
- } else {
- /* we have hit the top of a disconnected path. Try
- * to find parent and connect
- * note: racing with some other process renaming a
- * directory isn't much of a problem here. If someone
- * renames the directory, it will end up properly
- * connected, which is what we want
- */
- struct dentry *ppd;
- struct dentry *npd;
- char nbuf[NAME_MAX+1];
-
- down(&pd->d_inode->i_sem);
- ppd = CALL(nops,get_parent)(pd);
- up(&pd->d_inode->i_sem);
-
- if (IS_ERR(ppd)) {
- err = PTR_ERR(ppd);
- dprintk("find_exported_dentry: get_parent of %ld failed, err %d\n",
- pd->d_inode->i_ino, err);
- dput(pd);
- break;
- }
- dprintk("find_exported_dentry: find name of %lu in %lu\n", pd->d_inode->i_ino, ppd->d_inode->i_ino);
- err = CALL(nops,get_name)(ppd, nbuf, pd);
- if (err) {
- dput(ppd);
- dput(pd);
- if (err == -ENOENT)
- /* some race between get_parent and
- * get_name? just try again
- */
- continue;
- break;
- }
- dprintk("find_exported_dentry: found name: %s\n", nbuf);
- down(&ppd->d_inode->i_sem);
- npd = lookup_one_len(nbuf, ppd, strlen(nbuf));
- up(&ppd->d_inode->i_sem);
- if (IS_ERR(npd)) {
- err = PTR_ERR(npd);
- dprintk("find_exported_dentry: lookup failed: %d\n", err);
- dput(ppd);
- dput(pd);
- break;
- }
- /* we didn't really want npd, we really wanted
- * a side-effect of the lookup.
- * hopefully, npd == pd, though it isn't really
- * a problem if it isn't
- */
- if (npd == pd)
- noprogress = 0;
- else
- printk("find_exported_dentry: npd != pd\n");
- dput(npd);
- dput(ppd);
- if (IS_ROOT(pd)) {
- /* something went wrong, we have to give up */
- dput(pd);
- break;
- }
- }
- dput(pd);
- }
-
- if (target_dir->d_flags & DCACHE_DISCONNECTED) {
- /* something went wrong - oh-well */
- if (!err)
- err = -ESTALE;
- unlock_kernel();
- goto err_target;
- }
- /* if we weren't after a directory, have one more step to go */
- if (result != target_dir) {
- struct dentry *nresult;
- char nbuf[NAME_MAX+1];
- err = CALL(nops,get_name)(target_dir, nbuf, result);
- if (!err) {
- down(&target_dir->d_inode->i_sem);
- nresult = lookup_one_len(nbuf, target_dir, strlen(nbuf));
- up(&target_dir->d_inode->i_sem);
- if (!IS_ERR(nresult)) {
- if (nresult->d_inode) {
- dput(result);
- result = nresult;
- } else
- dput(nresult);
- }
- }
- }
- dput(target_dir);
- unlock_kernel();
- /* now result is properly connected, it is our best bet */
- if (acceptable(context, result))
- return result;
- /* one last try of the aliases.. */
- spin_lock(&dcache_lock);
- toput = NULL;
- head = &result->d_inode->i_dentry;
- list_for_each(le, head) {
- struct dentry *dentry = list_entry(le, struct dentry, d_alias);
- dget_locked(dentry);
- spin_unlock(&dcache_lock);
- if (toput) dput(toput);
- if (dentry != result &&
- acceptable(context, dentry)) {
- dput(result);
- dentry->d_vfs_flags |= DCACHE_REFERENCED;
- return dentry;
- }
- spin_lock(&dcache_lock);
- toput = dentry;
- }
- spin_unlock(&dcache_lock);
- if (toput)
- dput(toput);
-
- /* drat - I just cannot find anything acceptable */
- dput(result);
- return ERR_PTR(-ESTALE);
-
- err_target:
- dput(target_dir);
- err_result:
- dput(result);
- err_out:
- return ERR_PTR(err);
-}
-
-
-
-static struct dentry *get_parent(struct dentry *child)
-{
- /* get_parent cannot be supported generically, the locking
- * is too icky.
- * instead, we just return EACCES. If server reboots or inodes
- * get flushed, you lose
- */
- return ERR_PTR(-EACCES);
-}
-
-
-struct getdents_callback {
- char *name; /* name that was found. It already points to a
- buffer NAME_MAX+1 is size */
- unsigned long ino; /* the inum we are looking for */
- int found; /* inode matched? */
- int sequence; /* sequence counter */
-};
-
-/*
- * A rather strange filldir function to capture
- * the name matching the specified inode number.
- */
-static int filldir_one(void * __buf, const char * name, int len,
- loff_t pos, ino_t ino, unsigned int d_type)
-{
- struct getdents_callback *buf = __buf;
- int result = 0;
-
- buf->sequence++;
- if (buf->ino == ino) {
- memcpy(buf->name, name, len);
- buf->name[len] = '\0';
- buf->found = 1;
- result = -1;
- }
- return result;
-}
-
-/**
- * get_name - default export_operations->get_name function
- * @dentry: the directory in which to find a name
- * @name: a pointer to a %NAME_MAX+1 char buffer to store the name
- * @child: the dentry for the child directory.
- *
- * calls readdir on the parent until it finds an entry with
- * the same inode number as the child, and returns that.
- */
-static int get_name(struct dentry *dentry, char *name,
- struct dentry *child)
-{
- struct inode *dir = dentry->d_inode;
- int error;
- struct file file;
- struct getdents_callback buffer;
-
- error = -ENOTDIR;
- if (!dir || !S_ISDIR(dir->i_mode))
- goto out;
- error = -EINVAL;
- if (!dir->i_fop)
- goto out;
- /*
- * Open the directory ...
- */
- error = open_private_file(&file, dentry, O_RDONLY);
- if (error)
- goto out;
- error = -EINVAL;
- if (!file.f_op->readdir)
- goto out_close;
-
- buffer.name = name;
- buffer.ino = child->d_inode->i_ino;
- buffer.found = 0;
- buffer.sequence = 0;
- while (1) {
- int old_seq = buffer.sequence;
-
- error = vfs_readdir(&file, filldir_one, &buffer);
-
- if (error < 0)
- break;
-
- error = 0;
- if (buffer.found)
- break;
- error = -ENOENT;
- if (old_seq == buffer.sequence)
- break;
- }
-
-out_close:
- close_private_file(&file);
-out:
- return error;
-}
-
-
-static struct dentry *export_iget(struct super_block *sb, unsigned long ino, __u32 generation)
-{
-
- /* iget isn't really right if the inode is currently unallocated!!
- * This should really all be done inside each filesystem
- *
- * ext2fs' read_inode has been strengthed to return a bad_inode if
- * the inode had been deleted.
- *
- * Currently we don't know the generation for parent directory, so
- * a generation of 0 means "accept any"
- */
- struct inode *inode;
- struct dentry *result;
- if (ino == 0)
- return ERR_PTR(-ESTALE);
- inode = iget(sb, ino);
- if (inode == NULL)
- return ERR_PTR(-ENOMEM);
- if (is_bad_inode(inode)
- || (generation && inode->i_generation != generation)
- ) {
- /* we didn't find the right inode.. */
- dprintk("fh_verify: Inode %lu, Bad count: %d %d or version %u %u\n",
- inode->i_ino,
- inode->i_nlink, atomic_read(&inode->i_count),
- inode->i_generation,
- generation);
-
- iput(inode);
- return ERR_PTR(-ESTALE);
- }
- /* now to find a dentry.
- * If possible, get a well-connected one
- */
- result = d_alloc_anon(inode);
- if (!result) {
- iput(inode);
- return ERR_PTR(-ENOMEM);
- }
- result->d_vfs_flags |= DCACHE_REFERENCED;
- return result;
-}
-
-
-static struct dentry *get_object(struct super_block *sb, void *vobjp)
-{
- __u32 *objp = vobjp;
- unsigned long ino = objp[0];
- __u32 generation = objp[1];
-
- return export_iget(sb, ino, generation);
-}
-
-
-/**
- * export_encode_fh - default export_operations->encode_fh function
- * @dentry: the dentry to encode
- * @fh: where to store the file handle fragment
- * @max_len: maximum length to store there
- * @connectable: whether to store parent information
- *
- * This default encode_fh function assumes that the 32 inode number
- * is suitable for locating an inode, and that the generation number
- * can be used to check that it is still valid. It places them in the
- * filehandle fragment where export_decode_fh expects to find them.
- */
-static int export_encode_fh(struct dentry *dentry, __u32 *fh, int *max_len,
- int connectable)
-{
- struct inode * inode = dentry->d_inode;
- int len = *max_len;
- int type = 1;
-
- if (len < 2 || (connectable && len < 4))
- return 255;
-
- len = 2;
- fh[0] = inode->i_ino;
- fh[1] = inode->i_generation;
- if (connectable && !S_ISDIR(inode->i_mode)) {
- struct inode *parent;
-
- spin_lock(&dentry->d_lock);
- parent = dentry->d_parent->d_inode;
- fh[2] = parent->i_ino;
- fh[3] = parent->i_generation;
- spin_unlock(&dentry->d_lock);
- len = 4;
- type = 2;
- }
- *max_len = len;
- return type;
-}
-
-
-/**
- * export_decode_fh - default export_operations->decode_fh function
- * @sb: The superblock
- * @fh: pointer to the file handle fragment
- * @fh_len: length of file handle fragment
- * @acceptable: function for testing acceptability of dentrys
- * @context: context for @acceptable
- *
- * This is the default decode_fh() function.
- * a fileid_type of 1 indicates that the filehandlefragment
- * just contains an object identifier understood by get_dentry.
- * a fileid_type of 2 says that there is also a directory
- * identifier 8 bytes in to the filehandlefragement.
- */
-static struct dentry *export_decode_fh(struct super_block *sb, __u32 *fh, int fh_len,
- int fileid_type,
- int (*acceptable)(void *context, struct dentry *de),
- void *context)
-{
- __u32 parent[2];
- parent[0] = parent[1] = 0;
- if (fh_len < 2 || fileid_type > 2)
- return NULL;
- if (fileid_type == 2) {
- if (fh_len > 2) parent[0] = fh[2];
- if (fh_len > 3) parent[1] = fh[3];
- }
- return find_exported_dentry(sb, fh, parent,
- acceptable, context);
-}
-
-struct export_operations export_op_default = {
- .decode_fh = export_decode_fh,
- .encode_fh = export_encode_fh,
-
- .get_name = get_name,
- .get_parent = get_parent,
- .get_dentry = get_object,
-};
-
-EXPORT_SYMBOL(export_op_default);
-EXPORT_SYMBOL(find_exported_dentry);
-
-MODULE_LICENSE("GPL");
diff -Nru a/fs/libfs/Makefile b/fs/libfs/Makefile
--- /dev/null Wed Dec 31 16:00:00 1969
+++ b/fs/libfs/Makefile Sat Apr 5 21:29:54 2003
@@ -0,0 +1,3 @@
+
+obj-y += simple.o symlink.o
+obj-$(CONFIG_EXPORTFS) += export.o
diff -Nru a/fs/libfs/export.c b/fs/libfs/export.c
--- /dev/null Wed Dec 31 16:00:00 1969
+++ b/fs/libfs/export.c Sat Apr 5 21:29:54 2003
@@ -0,0 +1,536 @@
+
+#include <linux/fs.h>
+#include <linux/module.h>
+#include <linux/smp_lock.h>
+#include <linux/namei.h>
+
+struct export_operations export_op_default;
+
+#define CALL(ops,fun) ((ops->fun)?(ops->fun):export_op_default.fun)
+
+#define dprintk(fmt, args...) do{}while(0)
+
+/**
+ * find_exported_dentry - helper routine to implement export_operations->decode_fh
+ * @sb: The &super_block identifying the filesystem
+ * @obj: An opaque identifier of the object to be found - passed to
+ * get_inode
+ * @parent: An optional opqaue identifier of the parent of the object.
+ * @acceptable: A function used to test possible &dentries to see if they are
+ * acceptable
+ * @context: A parameter to @acceptable so that it knows on what basis to
+ * judge.
+ *
+ * find_exported_dentry is the central helper routine to enable file systems
+ * to provide the decode_fh() export_operation. It's main task is to take
+ * an &inode, find or create an appropriate &dentry structure, and possibly
+ * splice this into the dcache in the correct place.
+ *
+ * The decode_fh() operation provided by the filesystem should call
+ * find_exported_dentry() with the same parameters that it received except
+ * that instead of the file handle fragment, pointers to opaque identifiers
+ * for the object and optionally its parent are passed. The default decode_fh
+ * routine passes one pointer to the start of the filehandle fragment, and
+ * one 8 bytes into the fragment. It is expected that most filesystems will
+ * take this approach, though the offset to the parent identifier may well be
+ * different.
+ *
+ * find_exported_dentry() will call get_dentry to get an dentry pointer from
+ * the file system. If any &dentry in the d_alias list is acceptable, it will
+ * be returned. Otherwise find_exported_dentry() will attempt to splice a new
+ * &dentry into the dcache using get_name() and get_parent() to find the
+ * appropriate place.
+ */
+
+struct dentry *
+find_exported_dentry(struct super_block *sb, void *obj, void *parent,
+ int (*acceptable)(void *context, struct dentry *de),
+ void *context)
+{
+ struct dentry *result = NULL;
+ struct dentry *target_dir;
+ int err;
+ struct export_operations *nops = sb->s_export_op;
+ struct list_head *le, *head;
+ struct dentry *toput = NULL;
+ int noprogress;
+
+
+ /*
+ * Attempt to find the inode.
+ */
+ result = CALL(sb->s_export_op,get_dentry)(sb,obj);
+ err = -ESTALE;
+ if (result == NULL)
+ goto err_out;
+ if (IS_ERR(result)) {
+ err = PTR_ERR(result);
+ goto err_out;
+ }
+ if (S_ISDIR(result->d_inode->i_mode) &&
+ (result->d_flags & DCACHE_DISCONNECTED)) {
+ /* it is an unconnected directory, we must connect it */
+ ;
+ } else {
+ if (acceptable(context, result))
+ return result;
+ if (S_ISDIR(result->d_inode->i_mode)) {
+ /* there is no other dentry, so fail */
+ goto err_result;
+ }
+ /* try any other aliases */
+ spin_lock(&dcache_lock);
+ head = &result->d_inode->i_dentry;
+ list_for_each(le, head) {
+ struct dentry *dentry = list_entry(le, struct dentry, d_alias);
+ dget_locked(dentry);
+ spin_unlock(&dcache_lock);
+ if (toput)
+ dput(toput);
+ toput = NULL;
+ if (dentry != result &&
+ acceptable(context, dentry)) {
+ dput(result);
+ dentry->d_vfs_flags |= DCACHE_REFERENCED;
+ return dentry;
+ }
+ spin_lock(&dcache_lock);
+ toput = dentry;
+ }
+ spin_unlock(&dcache_lock);
+ if (toput)
+ dput(toput);
+ }
+
+ /* It's a directory, or we are required to confirm the file's
+ * location in the tree based on the parent information
+ */
+ dprintk("find_exported_dentry: need to look harder for %s/%d\n",sb->s_id,*(int*)obj);
+ if (S_ISDIR(result->d_inode->i_mode))
+ target_dir = dget(result);
+ else {
+ if (parent == NULL)
+ goto err_result;
+
+ target_dir = CALL(sb->s_export_op,get_dentry)(sb,parent);
+ if (IS_ERR(target_dir))
+ err = PTR_ERR(target_dir);
+ if (target_dir == NULL || IS_ERR(target_dir))
+ goto err_result;
+ }
+ /*
+ * Now we need to make sure that target_dir is properly connected.
+ * It may already be, as the flag isn't always updated when connection
+ * happens.
+ * So, we walk up parent links until we find a connected directory,
+ * or we run out of directories. Then we find the parent, find
+ * the name of the child in that parent, and do a lookup.
+ * This should connect the child into the parent
+ * We then repeat.
+ */
+
+ /* it is possible that a confused file system might not let us complete
+ * the path to the root. For example, if get_parent returns a directory
+ * in which we cannot find a name for the child. While this implies a
+ * very sick filesystem we don't want it to cause knfsd to spin. Hence
+ * the noprogress counter. If we go through the loop 10 times (2 is
+ * probably enough) without getting anywhere, we just give up
+ */
+ lock_kernel();
+ noprogress= 0;
+ while (target_dir->d_flags & DCACHE_DISCONNECTED && noprogress++ < 10) {
+ struct dentry *pd = target_dir;
+
+ dget(pd);
+ spin_lock(&pd->d_lock);
+ while (!IS_ROOT(pd) &&
+ (pd->d_parent->d_flags&DCACHE_DISCONNECTED)) {
+ struct dentry *parent = pd->d_parent;
+
+ dget(parent);
+ spin_unlock(&pd->d_lock);
+ dput(pd);
+ pd = parent;
+ spin_lock(&pd->d_lock);
+ }
+ spin_unlock(&pd->d_lock);
+
+ if (!IS_ROOT(pd)) {
+ /* must have found a connected parent - great */
+ pd->d_flags &= ~DCACHE_DISCONNECTED;
+ noprogress = 0;
+ } else if (pd == sb->s_root) {
+ printk(KERN_ERR "export: Eeek filesystem root is not connected, impossible\n");
+ pd->d_flags &= ~DCACHE_DISCONNECTED;
+ noprogress = 0;
+ } else {
+ /* we have hit the top of a disconnected path. Try
+ * to find parent and connect
+ * note: racing with some other process renaming a
+ * directory isn't much of a problem here. If someone
+ * renames the directory, it will end up properly
+ * connected, which is what we want
+ */
+ struct dentry *ppd;
+ struct dentry *npd;
+ char nbuf[NAME_MAX+1];
+
+ down(&pd->d_inode->i_sem);
+ ppd = CALL(nops,get_parent)(pd);
+ up(&pd->d_inode->i_sem);
+
+ if (IS_ERR(ppd)) {
+ err = PTR_ERR(ppd);
+ dprintk("find_exported_dentry: get_parent of %ld failed, err %d\n",
+ pd->d_inode->i_ino, err);
+ dput(pd);
+ break;
+ }
+ dprintk("find_exported_dentry: find name of %lu in %lu\n", pd->d_inode->i_ino, ppd->d_inode->i_ino);
+ err = CALL(nops,get_name)(ppd, nbuf, pd);
+ if (err) {
+ dput(ppd);
+ dput(pd);
+ if (err == -ENOENT)
+ /* some race between get_parent and
+ * get_name? just try again
+ */
+ continue;
+ break;
+ }
+ dprintk("find_exported_dentry: found name: %s\n", nbuf);
+ down(&ppd->d_inode->i_sem);
+ npd = lookup_one_len(nbuf, ppd, strlen(nbuf));
+ up(&ppd->d_inode->i_sem);
+ if (IS_ERR(npd)) {
+ err = PTR_ERR(npd);
+ dprintk("find_exported_dentry: lookup failed: %d\n", err);
+ dput(ppd);
+ dput(pd);
+ break;
+ }
+ /* we didn't really want npd, we really wanted
+ * a side-effect of the lookup.
+ * hopefully, npd == pd, though it isn't really
+ * a problem if it isn't
+ */
+ if (npd == pd)
+ noprogress = 0;
+ else
+ printk("find_exported_dentry: npd != pd\n");
+ dput(npd);
+ dput(ppd);
+ if (IS_ROOT(pd)) {
+ /* something went wrong, we have to give up */
+ dput(pd);
+ break;
+ }
+ }
+ dput(pd);
+ }
+
+ if (target_dir->d_flags & DCACHE_DISCONNECTED) {
+ /* something went wrong - oh-well */
+ if (!err)
+ err = -ESTALE;
+ unlock_kernel();
+ goto err_target;
+ }
+ /* if we weren't after a directory, have one more step to go */
+ if (result != target_dir) {
+ struct dentry *nresult;
+ char nbuf[NAME_MAX+1];
+ err = CALL(nops,get_name)(target_dir, nbuf, result);
+ if (!err) {
+ down(&target_dir->d_inode->i_sem);
+ nresult = lookup_one_len(nbuf, target_dir, strlen(nbuf));
+ up(&target_dir->d_inode->i_sem);
+ if (!IS_ERR(nresult)) {
+ if (nresult->d_inode) {
+ dput(result);
+ result = nresult;
+ } else
+ dput(nresult);
+ }
+ }
+ }
+ dput(target_dir);
+ unlock_kernel();
+ /* now result is properly connected, it is our best bet */
+ if (acceptable(context, result))
+ return result;
+ /* one last try of the aliases.. */
+ spin_lock(&dcache_lock);
+ toput = NULL;
+ head = &result->d_inode->i_dentry;
+ list_for_each(le, head) {
+ struct dentry *dentry = list_entry(le, struct dentry, d_alias);
+ dget_locked(dentry);
+ spin_unlock(&dcache_lock);
+ if (toput) dput(toput);
+ if (dentry != result &&
+ acceptable(context, dentry)) {
+ dput(result);
+ dentry->d_vfs_flags |= DCACHE_REFERENCED;
+ return dentry;
+ }
+ spin_lock(&dcache_lock);
+ toput = dentry;
+ }
+ spin_unlock(&dcache_lock);
+ if (toput)
+ dput(toput);
+
+ /* drat - I just cannot find anything acceptable */
+ dput(result);
+ return ERR_PTR(-ESTALE);
+
+ err_target:
+ dput(target_dir);
+ err_result:
+ dput(result);
+ err_out:
+ return ERR_PTR(err);
+}
+
+
+
+static struct dentry *get_parent(struct dentry *child)
+{
+ /* get_parent cannot be supported generically, the locking
+ * is too icky.
+ * instead, we just return EACCES. If server reboots or inodes
+ * get flushed, you lose
+ */
+ return ERR_PTR(-EACCES);
+}
+
+
+struct getdents_callback {
+ char *name; /* name that was found. It already points to a
+ buffer NAME_MAX+1 is size */
+ unsigned long ino; /* the inum we are looking for */
+ int found; /* inode matched? */
+ int sequence; /* sequence counter */
+};
+
+/*
+ * A rather strange filldir function to capture
+ * the name matching the specified inode number.
+ */
+static int filldir_one(void * __buf, const char * name, int len,
+ loff_t pos, ino_t ino, unsigned int d_type)
+{
+ struct getdents_callback *buf = __buf;
+ int result = 0;
+
+ buf->sequence++;
+ if (buf->ino == ino) {
+ memcpy(buf->name, name, len);
+ buf->name[len] = '\0';
+ buf->found = 1;
+ result = -1;
+ }
+ return result;
+}
+
+/**
+ * get_name - default export_operations->get_name function
+ * @dentry: the directory in which to find a name
+ * @name: a pointer to a %NAME_MAX+1 char buffer to store the name
+ * @child: the dentry for the child directory.
+ *
+ * calls readdir on the parent until it finds an entry with
+ * the same inode number as the child, and returns that.
+ */
+static int get_name(struct dentry *dentry, char *name,
+ struct dentry *child)
+{
+ struct inode *dir = dentry->d_inode;
+ int error;
+ struct file file;
+ struct getdents_callback buffer;
+
+ error = -ENOTDIR;
+ if (!dir || !S_ISDIR(dir->i_mode))
+ goto out;
+ error = -EINVAL;
+ if (!dir->i_fop)
+ goto out;
+ /*
+ * Open the directory ...
+ */
+ error = open_private_file(&file, dentry, O_RDONLY);
+ if (error)
+ goto out;
+ error = -EINVAL;
+ if (!file.f_op->readdir)
+ goto out_close;
+
+ buffer.name = name;
+ buffer.ino = child->d_inode->i_ino;
+ buffer.found = 0;
+ buffer.sequence = 0;
+ while (1) {
+ int old_seq = buffer.sequence;
+
+ error = vfs_readdir(&file, filldir_one, &buffer);
+
+ if (error < 0)
+ break;
+
+ error = 0;
+ if (buffer.found)
+ break;
+ error = -ENOENT;
+ if (old_seq == buffer.sequence)
+ break;
+ }
+
+out_close:
+ close_private_file(&file);
+out:
+ return error;
+}
+
+
+static struct dentry *export_iget(struct super_block *sb, unsigned long ino, __u32 generation)
+{
+
+ /* iget isn't really right if the inode is currently unallocated!!
+ * This should really all be done inside each filesystem
+ *
+ * ext2fs' read_inode has been strengthed to return a bad_inode if
+ * the inode had been deleted.
+ *
+ * Currently we don't know the generation for parent directory, so
+ * a generation of 0 means "accept any"
+ */
+ struct inode *inode;
+ struct dentry *result;
+ if (ino == 0)
+ return ERR_PTR(-ESTALE);
+ inode = iget(sb, ino);
+ if (inode == NULL)
+ return ERR_PTR(-ENOMEM);
+ if (is_bad_inode(inode)
+ || (generation && inode->i_generation != generation)
+ ) {
+ /* we didn't find the right inode.. */
+ dprintk("fh_verify: Inode %lu, Bad count: %d %d or version %u %u\n",
+ inode->i_ino,
+ inode->i_nlink, atomic_read(&inode->i_count),
+ inode->i_generation,
+ generation);
+
+ iput(inode);
+ return ERR_PTR(-ESTALE);
+ }
+ /* now to find a dentry.
+ * If possible, get a well-connected one
+ */
+ result = d_alloc_anon(inode);
+ if (!result) {
+ iput(inode);
+ return ERR_PTR(-ENOMEM);
+ }
+ result->d_vfs_flags |= DCACHE_REFERENCED;
+ return result;
+}
+
+
+static struct dentry *get_object(struct super_block *sb, void *vobjp)
+{
+ __u32 *objp = vobjp;
+ unsigned long ino = objp[0];
+ __u32 generation = objp[1];
+
+ return export_iget(sb, ino, generation);
+}
+
+
+/**
+ * export_encode_fh - default export_operations->encode_fh function
+ * @dentry: the dentry to encode
+ * @fh: where to store the file handle fragment
+ * @max_len: maximum length to store there
+ * @connectable: whether to store parent information
+ *
+ * This default encode_fh function assumes that the 32 inode number
+ * is suitable for locating an inode, and that the generation number
+ * can be used to check that it is still valid. It places them in the
+ * filehandle fragment where export_decode_fh expects to find them.
+ */
+static int export_encode_fh(struct dentry *dentry, __u32 *fh, int *max_len,
+ int connectable)
+{
+ struct inode * inode = dentry->d_inode;
+ int len = *max_len;
+ int type = 1;
+
+ if (len < 2 || (connectable && len < 4))
+ return 255;
+
+ len = 2;
+ fh[0] = inode->i_ino;
+ fh[1] = inode->i_generation;
+ if (connectable && !S_ISDIR(inode->i_mode)) {
+ struct inode *parent;
+
+ spin_lock(&dentry->d_lock);
+ parent = dentry->d_parent->d_inode;
+ fh[2] = parent->i_ino;
+ fh[3] = parent->i_generation;
+ spin_unlock(&dentry->d_lock);
+ len = 4;
+ type = 2;
+ }
+ *max_len = len;
+ return type;
+}
+
+
+/**
+ * export_decode_fh - default export_operations->decode_fh function
+ * @sb: The superblock
+ * @fh: pointer to the file handle fragment
+ * @fh_len: length of file handle fragment
+ * @acceptable: function for testing acceptability of dentrys
+ * @context: context for @acceptable
+ *
+ * This is the default decode_fh() function.
+ * a fileid_type of 1 indicates that the filehandlefragment
+ * just contains an object identifier understood by get_dentry.
+ * a fileid_type of 2 says that there is also a directory
+ * identifier 8 bytes in to the filehandlefragement.
+ */
+static struct dentry *export_decode_fh(struct super_block *sb, __u32 *fh, int fh_len,
+ int fileid_type,
+ int (*acceptable)(void *context, struct dentry *de),
+ void *context)
+{
+ __u32 parent[2];
+ parent[0] = parent[1] = 0;
+ if (fh_len < 2 || fileid_type > 2)
+ return NULL;
+ if (fileid_type == 2) {
+ if (fh_len > 2) parent[0] = fh[2];
+ if (fh_len > 3) parent[1] = fh[3];
+ }
+ return find_exported_dentry(sb, fh, parent,
+ acceptable, context);
+}
+
+struct export_operations export_op_default = {
+ .decode_fh = export_decode_fh,
+ .encode_fh = export_encode_fh,
+
+ .get_name = get_name,
+ .get_parent = get_parent,
+ .get_dentry = get_object,
+};
+
+EXPORT_SYMBOL(export_op_default);
+EXPORT_SYMBOL(find_exported_dentry);
+
+MODULE_LICENSE("GPL");
diff -Nru a/fs/libfs/simple.c b/fs/libfs/simple.c
--- /dev/null Wed Dec 31 16:00:00 1969
+++ b/fs/libfs/simple.c Sat Apr 5 21:29:54 2003
@@ -0,0 +1,334 @@
+/*
+ * fs/libfs.c
+ * Library for filesystems writers.
+ */
+
+#include <linux/pagemap.h>
+#include <linux/vfs.h>
+
+int simple_getattr(struct vfsmount *mnt, struct dentry *dentry,
+ struct kstat *stat)
+{
+ struct inode *inode = dentry->d_inode;
+ generic_fillattr(inode, stat);
+ stat->blocks = inode->i_mapping->nrpages << (PAGE_CACHE_SHIFT - 9);
+ return 0;
+}
+
+int simple_statfs(struct super_block *sb, struct statfs *buf)
+{
+ buf->f_type = sb->s_magic;
+ buf->f_bsize = PAGE_CACHE_SIZE;
+ buf->f_namelen = NAME_MAX;
+ return 0;
+}
+
+/*
+ * Lookup the data. This is trivial - if the dentry didn't already
+ * exist, we know it is negative.
+ */
+
+struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry)
+{
+ d_add(dentry, NULL);
+ return NULL;
+}
+
+int simple_sync_file(struct file * file, struct dentry *dentry, int datasync)
+{
+ return 0;
+}
+
+int dcache_dir_open(struct inode *inode, struct file *file)
+{
+ static struct qstr cursor_name = {.len = 1, .name = "."};
+
+ file->private_data = d_alloc(file->f_dentry, &cursor_name);
+
+ return file->private_data ? 0 : -ENOMEM;
+}
+
+int dcache_dir_close(struct inode *inode, struct file *file)
+{
+ dput(file->private_data);
+ return 0;
+}
+
+loff_t dcache_dir_lseek(struct file *file, loff_t offset, int origin)
+{
+ down(&file->f_dentry->d_inode->i_sem);
+ switch (origin) {
+ case 1:
+ offset += file->f_pos;
+ case 0:
+ if (offset >= 0)
+ break;
+ default:
+ up(&file->f_dentry->d_inode->i_sem);
+ return -EINVAL;
+ }
+ if (offset != file->f_pos) {
+ file->f_pos = offset;
+ if (file->f_pos >= 2) {
+ struct list_head *p;
+ struct dentry *cursor = file->private_data;
+ loff_t n = file->f_pos - 2;
+
+ spin_lock(&dcache_lock);
+ p = file->f_dentry->d_subdirs.next;
+ while (n && p != &file->f_dentry->d_subdirs) {
+ struct dentry *next;
+ next = list_entry(p, struct dentry, d_child);
+ if (!d_unhashed(next) && next->d_inode)
+ n--;
+ p = p->next;
+ }
+ list_del(&cursor->d_child);
+ list_add_tail(&cursor->d_child, p);
+ spin_unlock(&dcache_lock);
+ }
+ }
+ up(&file->f_dentry->d_inode->i_sem);
+ return offset;
+}
+
+/* Relationship between i_mode and the DT_xxx types */
+static inline unsigned char dt_type(struct inode *inode)
+{
+ return (inode->i_mode >> 12) & 15;
+}
+
+/*
+ * Directory is locked and all positive dentries in it are safe, since
+ * for ramfs-type trees they can't go away without unlink() or rmdir(),
+ * both impossible due to the lock on directory.
+ */
+
+int dcache_readdir(struct file * filp, void * dirent, filldir_t filldir)
+{
+ struct dentry *dentry = filp->f_dentry;
+ struct dentry *cursor = filp->private_data;
+ struct list_head *p, *q = &cursor->d_child;
+ ino_t ino;
+ int i = filp->f_pos;
+
+ switch (i) {
+ case 0:
+ ino = dentry->d_inode->i_ino;
+ if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
+ break;
+ filp->f_pos++;
+ i++;
+ /* fallthrough */
+ case 1:
+ ino = parent_ino(dentry);
+ if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
+ break;
+ filp->f_pos++;
+ i++;
+ /* fallthrough */
+ default:
+ spin_lock(&dcache_lock);
+ if (filp->f_pos == 2) {
+ list_del(q);
+ list_add(q, &dentry->d_subdirs);
+ }
+ for (p=q->next; p != &dentry->d_subdirs; p=p->next) {
+ struct dentry *next;
+ next = list_entry(p, struct dentry, d_child);
+ if (d_unhashed(next) || !next->d_inode)
+ continue;
+
+ spin_unlock(&dcache_lock);
+ if (filldir(dirent, next->d_name.name, next->d_name.len, filp->f_pos, next->d_inode->i_ino, dt_type(next->d_inode)) < 0)
+ return 0;
+ spin_lock(&dcache_lock);
+ /* next is still alive */
+ list_del(q);
+ list_add(q, p);
+ p = q;
+ filp->f_pos++;
+ }
+ spin_unlock(&dcache_lock);
+ }
+ return 0;
+}
+
+ssize_t generic_read_dir(struct file *filp, char *buf, size_t siz, loff_t *ppos)
+{
+ return -EISDIR;
+}
+
+struct file_operations simple_dir_operations = {
+ .open = dcache_dir_open,
+ .release = dcache_dir_close,
+ .llseek = dcache_dir_lseek,
+ .read = generic_read_dir,
+ .readdir = dcache_readdir,
+};
+
+struct inode_operations simple_dir_inode_operations = {
+ .lookup = simple_lookup,
+};
+
+/*
+ * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that
+ * will never be mountable)
+ */
+struct super_block *
+get_sb_pseudo(struct file_system_type *fs_type, char *name,
+ struct super_operations *ops, unsigned long magic)
+{
+ struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL);
+ static struct super_operations default_ops = {.statfs = simple_statfs};
+ struct dentry *dentry;
+ struct inode *root;
+ struct qstr d_name = {.name = name, .len = strlen(name)};
+
+ if (IS_ERR(s))
+ return s;
+
+ s->s_flags = MS_NOUSER;
+ s->s_maxbytes = ~0ULL;
+ s->s_blocksize = 1024;
+ s->s_blocksize_bits = 10;
+ s->s_magic = magic;
+ s->s_op = ops ? ops : &default_ops;
+ root = new_inode(s);
+ if (!root)
+ goto Enomem;
+ root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR;
+ root->i_uid = root->i_gid = 0;
+ root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME;
+ dentry = d_alloc(NULL, &d_name);
+ if (!dentry) {
+ iput(root);
+ goto Enomem;
+ }
+ dentry->d_sb = s;
+ dentry->d_parent = dentry;
+ d_instantiate(dentry, root);
+ s->s_root = dentry;
+ s->s_flags |= MS_ACTIVE;
+ return s;
+
+Enomem:
+ up_write(&s->s_umount);
+ deactivate_super(s);
+ return ERR_PTR(-ENOMEM);
+}
+
+int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
+{
+ struct inode *inode = old_dentry->d_inode;
+
+ inode->i_nlink++;
+ atomic_inc(&inode->i_count);
+ dget(dentry);
+ d_instantiate(dentry, inode);
+ return 0;
+}
+
+static inline int simple_positive(struct dentry *dentry)
+{
+ return dentry->d_inode && !d_unhashed(dentry);
+}
+
+int simple_empty(struct dentry *dentry)
+{
+ struct dentry *child;
+ int ret = 0;
+
+ spin_lock(&dcache_lock);
+ list_for_each_entry(child, &dentry->d_subdirs, d_child)
+ if (simple_positive(child))
+ goto out;
+ ret = 1;
+out:
+ spin_unlock(&dcache_lock);
+ return ret;
+}
+
+int simple_unlink(struct inode *dir, struct dentry *dentry)
+{
+ struct inode *inode = dentry->d_inode;
+
+ inode->i_nlink--;
+ dput(dentry);
+ return 0;
+}
+
+int simple_rmdir(struct inode *dir, struct dentry *dentry)
+{
+ if (!simple_empty(dentry))
+ return -ENOTEMPTY;
+
+ dentry->d_inode->i_nlink--;
+ simple_unlink(dir, dentry);
+ dir->i_nlink--;
+ return 0;
+}
+
+int simple_rename(struct inode *old_dir, struct dentry *old_dentry,
+ struct inode *new_dir, struct dentry *new_dentry)
+{
+ int they_are_dirs = S_ISDIR(old_dentry->d_inode->i_mode);
+
+ if (!simple_empty(new_dentry))
+ return -ENOTEMPTY;
+
+ if (new_dentry->d_inode) {
+ simple_unlink(new_dir, new_dentry);
+ if (they_are_dirs)
+ old_dir->i_nlink--;
+ } else if (they_are_dirs) {
+ old_dir->i_nlink--;
+ new_dir->i_nlink++;
+ }
+ return 0;
+}
+
+int simple_readpage(struct file *file, struct page *page)
+{
+ void *kaddr;
+
+ if (PageUptodate(page))
+ goto out;
+
+ kaddr = kmap_atomic(page, KM_USER0);
+ memset(kaddr, 0, PAGE_CACHE_SIZE);
+ kunmap_atomic(kaddr, KM_USER0);
+ flush_dcache_page(page);
+ SetPageUptodate(page);
+out:
+ unlock_page(page);
+ return 0;
+}
+
+int simple_prepare_write(struct file *file, struct page *page,
+ unsigned from, unsigned to)
+{
+ if (!PageUptodate(page)) {
+ if (to - from != PAGE_CACHE_SIZE) {
+ void *kaddr = kmap_atomic(page, KM_USER0);
+ memset(kaddr, 0, from);
+ memset(kaddr + to, 0, PAGE_CACHE_SIZE - to);
+ flush_dcache_page(page);
+ kunmap_atomic(kaddr, KM_USER0);
+ }
+ SetPageUptodate(page);
+ }
+ return 0;
+}
+
+int simple_commit_write(struct file *file, struct page *page,
+ unsigned offset, unsigned to)
+{
+ struct inode *inode = page->mapping->host;
+ loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
+
+ if (pos > inode->i_size)
+ inode->i_size = pos;
+ set_page_dirty(page);
+ return 0;
+}
diff -Nru a/fs/libfs/symlink.c b/fs/libfs/symlink.c
--- /dev/null Wed Dec 31 16:00:00 1969
+++ b/fs/libfs/symlink.c Sat Apr 5 21:29:54 2003
@@ -0,0 +1,100 @@
+/* from fs/namei.c, written by Al Viro */
+
+#include <linux/kernel.h>
+#include <linux/fs.h>
+#include <linux/pagemap.h>
+
+
+/* get the link contents into pagecache */
+static char *page_getlink(struct dentry *dentry, struct page **ppage)
+{
+ struct page * page;
+ struct address_space *mapping = dentry->d_inode->i_mapping;
+ page = read_cache_page(mapping, 0, (filler_t *)mapping->a_ops->readpage,
+ NULL);
+ if (unlikely(IS_ERR(page)))
+ goto sync_fail;
+ wait_on_page_locked(page);
+ if (unlikely(!PageUptodate(page)))
+ goto async_fail;
+ *ppage = page;
+ return kmap(page);
+
+async_fail:
+ page_cache_release(page);
+ return ERR_PTR(-EIO);
+
+sync_fail:
+ return (char*)page;
+}
+
+int page_readlink(struct dentry *dentry, char *buffer, int buflen)
+{
+ struct page *page = NULL;
+ char *s = page_getlink(dentry, &page);
+ int res = vfs_readlink(dentry,buffer,buflen,s);
+ if (likely(page != NULL)) {
+ kunmap(page);
+ page_cache_release(page);
+ }
+ return res;
+}
+
+int page_follow_link(struct dentry *dentry, struct nameidata *nd)
+{
+ struct page *page = NULL;
+ char *s = page_getlink(dentry, &page);
+ int res = vfs_follow_link(nd, s);
+ if (likely(page != NULL)) {
+ kunmap(page);
+ page_cache_release(page);
+ }
+ return res;
+}
+
+int page_symlink(struct inode *inode, const char *symname, int len)
+{
+ struct address_space *mapping = inode->i_mapping;
+ struct page *page = grab_cache_page(mapping, 0);
+ int err = -ENOMEM;
+ char *kaddr;
+
+ if (unlikely(!page))
+ goto fail;
+ err = mapping->a_ops->prepare_write(NULL, page, 0, len-1);
+ if (unlikely(err))
+ goto fail_map;
+ kaddr = kmap_atomic(page, KM_USER0);
+ memcpy(kaddr, symname, len-1);
+ kunmap_atomic(kaddr, KM_USER0);
+ mapping->a_ops->commit_write(NULL, page, 0, len-1);
+
+ /*
+ * Notice that we are _not_ going to block here - end of page is
+ * unmapped, so this will only try to map the rest of page, see
+ * that it is unmapped (typically even will not look into inode -
+ * ->i_size will be enough for everything) and zero it out.
+ * OTOH it's obviously correct and should make the page up-to-date.
+ */
+ if (!PageUptodate(page)) {
+ err = mapping->a_ops->readpage(NULL, page);
+ wait_on_page_locked(page);
+ } else {
+ unlock_page(page);
+ }
+ page_cache_release(page);
+ if (unlikely(err < 0))
+ goto fail;
+ mark_inode_dirty(inode);
+ return 0;
+fail_map:
+ unlock_page(page);
+ page_cache_release(page);
+fail:
+ return err;
+}
+
+struct inode_operations page_symlink_inode_operations = {
+ .readlink = page_readlink,
+ .follow_link = page_follow_link,
+};
diff -Nru a/fs/libfs.c b/fs/libfs.c
--- a/fs/libfs.c Sat Apr 5 21:29:54 2003
+++ /dev/null Wed Dec 31 16:00:00 1969
@@ -1,334 +0,0 @@
-/*
- * fs/libfs.c
- * Library for filesystems writers.
- */
-
-#include <linux/pagemap.h>
-#include <linux/vfs.h>
-
-int simple_getattr(struct vfsmount *mnt, struct dentry *dentry,
- struct kstat *stat)
-{
- struct inode *inode = dentry->d_inode;
- generic_fillattr(inode, stat);
- stat->blocks = inode->i_mapping->nrpages << (PAGE_CACHE_SHIFT - 9);
- return 0;
-}
-
-int simple_statfs(struct super_block *sb, struct statfs *buf)
-{
- buf->f_type = sb->s_magic;
- buf->f_bsize = PAGE_CACHE_SIZE;
- buf->f_namelen = NAME_MAX;
- return 0;
-}
-
-/*
- * Lookup the data. This is trivial - if the dentry didn't already
- * exist, we know it is negative.
- */
-
-struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry)
-{
- d_add(dentry, NULL);
- return NULL;
-}
-
-int simple_sync_file(struct file * file, struct dentry *dentry, int datasync)
-{
- return 0;
-}
-
-int dcache_dir_open(struct inode *inode, struct file *file)
-{
- static struct qstr cursor_name = {.len = 1, .name = "."};
-
- file->private_data = d_alloc(file->f_dentry, &cursor_name);
-
- return file->private_data ? 0 : -ENOMEM;
-}
-
-int dcache_dir_close(struct inode *inode, struct file *file)
-{
- dput(file->private_data);
- return 0;
-}
-
-loff_t dcache_dir_lseek(struct file *file, loff_t offset, int origin)
-{
- down(&file->f_dentry->d_inode->i_sem);
- switch (origin) {
- case 1:
- offset += file->f_pos;
- case 0:
- if (offset >= 0)
- break;
- default:
- up(&file->f_dentry->d_inode->i_sem);
- return -EINVAL;
- }
- if (offset != file->f_pos) {
- file->f_pos = offset;
- if (file->f_pos >= 2) {
- struct list_head *p;
- struct dentry *cursor = file->private_data;
- loff_t n = file->f_pos - 2;
-
- spin_lock(&dcache_lock);
- p = file->f_dentry->d_subdirs.next;
- while (n && p != &file->f_dentry->d_subdirs) {
- struct dentry *next;
- next = list_entry(p, struct dentry, d_child);
- if (!d_unhashed(next) && next->d_inode)
- n--;
- p = p->next;
- }
- list_del(&cursor->d_child);
- list_add_tail(&cursor->d_child, p);
- spin_unlock(&dcache_lock);
- }
- }
- up(&file->f_dentry->d_inode->i_sem);
- return offset;
-}
-
-/* Relationship between i_mode and the DT_xxx types */
-static inline unsigned char dt_type(struct inode *inode)
-{
- return (inode->i_mode >> 12) & 15;
-}
-
-/*
- * Directory is locked and all positive dentries in it are safe, since
- * for ramfs-type trees they can't go away without unlink() or rmdir(),
- * both impossible due to the lock on directory.
- */
-
-int dcache_readdir(struct file * filp, void * dirent, filldir_t filldir)
-{
- struct dentry *dentry = filp->f_dentry;
- struct dentry *cursor = filp->private_data;
- struct list_head *p, *q = &cursor->d_child;
- ino_t ino;
- int i = filp->f_pos;
-
- switch (i) {
- case 0:
- ino = dentry->d_inode->i_ino;
- if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
- break;
- filp->f_pos++;
- i++;
- /* fallthrough */
- case 1:
- ino = parent_ino(dentry);
- if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
- break;
- filp->f_pos++;
- i++;
- /* fallthrough */
- default:
- spin_lock(&dcache_lock);
- if (filp->f_pos == 2) {
- list_del(q);
- list_add(q, &dentry->d_subdirs);
- }
- for (p=q->next; p != &dentry->d_subdirs; p=p->next) {
- struct dentry *next;
- next = list_entry(p, struct dentry, d_child);
- if (d_unhashed(next) || !next->d_inode)
- continue;
-
- spin_unlock(&dcache_lock);
- if (filldir(dirent, next->d_name.name, next->d_name.len, filp->f_pos, next->d_inode->i_ino, dt_type(next->d_inode)) < 0)
- return 0;
- spin_lock(&dcache_lock);
- /* next is still alive */
- list_del(q);
- list_add(q, p);
- p = q;
- filp->f_pos++;
- }
- spin_unlock(&dcache_lock);
- }
- return 0;
-}
-
-ssize_t generic_read_dir(struct file *filp, char *buf, size_t siz, loff_t *ppos)
-{
- return -EISDIR;
-}
-
-struct file_operations simple_dir_operations = {
- .open = dcache_dir_open,
- .release = dcache_dir_close,
- .llseek = dcache_dir_lseek,
- .read = generic_read_dir,
- .readdir = dcache_readdir,
-};
-
-struct inode_operations simple_dir_inode_operations = {
- .lookup = simple_lookup,
-};
-
-/*
- * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that
- * will never be mountable)
- */
-struct super_block *
-get_sb_pseudo(struct file_system_type *fs_type, char *name,
- struct super_operations *ops, unsigned long magic)
-{
- struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL);
- static struct super_operations default_ops = {.statfs = simple_statfs};
- struct dentry *dentry;
- struct inode *root;
- struct qstr d_name = {.name = name, .len = strlen(name)};
-
- if (IS_ERR(s))
- return s;
-
- s->s_flags = MS_NOUSER;
- s->s_maxbytes = ~0ULL;
- s->s_blocksize = 1024;
- s->s_blocksize_bits = 10;
- s->s_magic = magic;
- s->s_op = ops ? ops : &default_ops;
- root = new_inode(s);
- if (!root)
- goto Enomem;
- root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR;
- root->i_uid = root->i_gid = 0;
- root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME;
- dentry = d_alloc(NULL, &d_name);
- if (!dentry) {
- iput(root);
- goto Enomem;
- }
- dentry->d_sb = s;
- dentry->d_parent = dentry;
- d_instantiate(dentry, root);
- s->s_root = dentry;
- s->s_flags |= MS_ACTIVE;
- return s;
-
-Enomem:
- up_write(&s->s_umount);
- deactivate_super(s);
- return ERR_PTR(-ENOMEM);
-}
-
-int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
-{
- struct inode *inode = old_dentry->d_inode;
-
- inode->i_nlink++;
- atomic_inc(&inode->i_count);
- dget(dentry);
- d_instantiate(dentry, inode);
- return 0;
-}
-
-static inline int simple_positive(struct dentry *dentry)
-{
- return dentry->d_inode && !d_unhashed(dentry);
-}
-
-int simple_empty(struct dentry *dentry)
-{
- struct dentry *child;
- int ret = 0;
-
- spin_lock(&dcache_lock);
- list_for_each_entry(child, &dentry->d_subdirs, d_child)
- if (simple_positive(child))
- goto out;
- ret = 1;
-out:
- spin_unlock(&dcache_lock);
- return ret;
-}
-
-int simple_unlink(struct inode *dir, struct dentry *dentry)
-{
- struct inode *inode = dentry->d_inode;
-
- inode->i_nlink--;
- dput(dentry);
- return 0;
-}
-
-int simple_rmdir(struct inode *dir, struct dentry *dentry)
-{
- if (!simple_empty(dentry))
- return -ENOTEMPTY;
-
- dentry->d_inode->i_nlink--;
- simple_unlink(dir, dentry);
- dir->i_nlink--;
- return 0;
-}
-
-int simple_rename(struct inode *old_dir, struct dentry *old_dentry,
- struct inode *new_dir, struct dentry *new_dentry)
-{
- int they_are_dirs = S_ISDIR(old_dentry->d_inode->i_mode);
-
- if (!simple_empty(new_dentry))
- return -ENOTEMPTY;
-
- if (new_dentry->d_inode) {
- simple_unlink(new_dir, new_dentry);
- if (they_are_dirs)
- old_dir->i_nlink--;
- } else if (they_are_dirs) {
- old_dir->i_nlink--;
- new_dir->i_nlink++;
- }
- return 0;
-}
-
-int simple_readpage(struct file *file, struct page *page)
-{
- void *kaddr;
-
- if (PageUptodate(page))
- goto out;
-
- kaddr = kmap_atomic(page, KM_USER0);
- memset(kaddr, 0, PAGE_CACHE_SIZE);
- kunmap_atomic(kaddr, KM_USER0);
- flush_dcache_page(page);
- SetPageUptodate(page);
-out:
- unlock_page(page);
- return 0;
-}
-
-int simple_prepare_write(struct file *file, struct page *page,
- unsigned from, unsigned to)
-{
- if (!PageUptodate(page)) {
- if (to - from != PAGE_CACHE_SIZE) {
- void *kaddr = kmap_atomic(page, KM_USER0);
- memset(kaddr, 0, from);
- memset(kaddr + to, 0, PAGE_CACHE_SIZE - to);
- flush_dcache_page(page);
- kunmap_atomic(kaddr, KM_USER0);
- }
- SetPageUptodate(page);
- }
- return 0;
-}
-
-int simple_commit_write(struct file *file, struct page *page,
- unsigned offset, unsigned to)
-{
- struct inode *inode = page->mapping->host;
- loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
-
- if (pos > inode->i_size)
- inode->i_size = pos;
- set_page_dirty(page);
- return 0;
-}
diff -Nru a/fs/namei.c b/fs/namei.c
--- a/fs/namei.c Sat Apr 5 21:29:54 2003
+++ b/fs/namei.c Sat Apr 5 21:29:54 2003
@@ -2093,8 +2093,7 @@
return len;
}
-static inline int
-__vfs_follow_link(struct nameidata *nd, const char *link)
+int vfs_follow_link(struct nameidata *nd, const char *link)
{
int res = 0;
char *name;
@@ -2128,101 +2127,3 @@
path_release(nd);
return PTR_ERR(link);
}
-
-int vfs_follow_link(struct nameidata *nd, const char *link)
-{
- return __vfs_follow_link(nd, link);
-}
-
-/* get the link contents into pagecache */
-static char *page_getlink(struct dentry * dentry, struct page **ppage)
-{
- struct page * page;
- struct address_space *mapping = dentry->d_inode->i_mapping;
- page = read_cache_page(mapping, 0, (filler_t *)mapping->a_ops->readpage,
- NULL);
- if (IS_ERR(page))
- goto sync_fail;
- wait_on_page_locked(page);
- if (!PageUptodate(page))
- goto async_fail;
- *ppage = page;
- return kmap(page);
-
-async_fail:
- page_cache_release(page);
- return ERR_PTR(-EIO);
-
-sync_fail:
- return (char*)page;
-}
-
-int page_readlink(struct dentry *dentry, char *buffer, int buflen)
-{
- struct page *page = NULL;
- char *s = page_getlink(dentry, &page);
- int res = vfs_readlink(dentry,buffer,buflen,s);
- if (page) {
- kunmap(page);
- page_cache_release(page);
- }
- return res;
-}
-
-int page_follow_link(struct dentry *dentry, struct nameidata *nd)
-{
- struct page *page = NULL;
- char *s = page_getlink(dentry, &page);
- int res = __vfs_follow_link(nd, s);
- if (page) {
- kunmap(page);
- page_cache_release(page);
- }
- return res;
-}
-
-int page_symlink(struct inode *inode, const char *symname, int len)
-{
- struct address_space *mapping = inode->i_mapping;
- struct page *page = grab_cache_page(mapping, 0);
- int err = -ENOMEM;
- char *kaddr;
-
- if (!page)
- goto fail;
- err = mapping->a_ops->prepare_write(NULL, page, 0, len-1);
- if (err)
- goto fail_map;
- kaddr = kmap_atomic(page, KM_USER0);
- memcpy(kaddr, symname, len-1);
- kunmap_atomic(kaddr, KM_USER0);
- mapping->a_ops->commit_write(NULL, page, 0, len-1);
- /*
- * Notice that we are _not_ going to block here - end of page is
- * unmapped, so this will only try to map the rest of page, see
- * that it is unmapped (typically even will not look into inode -
- * ->i_size will be enough for everything) and zero it out.
- * OTOH it's obviously correct and should make the page up-to-date.
- */
- if (!PageUptodate(page)) {
- err = mapping->a_ops->readpage(NULL, page);
- wait_on_page_locked(page);
- } else {
- unlock_page(page);
- }
- page_cache_release(page);
- if (err < 0)
- goto fail;
- mark_inode_dirty(inode);
- return 0;
-fail_map:
- unlock_page(page);
- page_cache_release(page);
-fail:
- return err;
-}
-
-struct inode_operations page_symlink_inode_operations = {
- .readlink = page_readlink,
- .follow_link = page_follow_link,
-};
===================================================================
This BitKeeper patch contains the following changesets:
1.1034
## Wrapped with gzip_uu ##
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