[PATCH 002 of 8] knfsd: exportfs: remove iget abuse

NeilBrown
2007-05-15T07:17:28Z

When the exportfs interface was added the expectation was that
filesystems provide an operation to convert from a file handle
to an inode/dentry, but it kept a backwards compat option that
still calls into iget.

Calling into iget from non-filesystem code is very bad, because
it gives too little information to filesystem, and simply crashes
if the filesystem doesn't implement the ->read_inode routine.

Fortunately there are only two filesystems left using this fallback:
efs and jfs. This patch moves a copy of export_iget to each
of those to implement the get_dentry method.

While this is a temporary increase of lines of code in the kernel
it allows for a much cleaner interface and important code restructuring
in later patches.

Cc: shaggy@austin.ibm.com
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Neil Brown <neilb@suse.de>

### Diffstat output
./fs/efs/namei.c | 32 ++++++++++++++++++++++++++
./fs/efs/super.c | 1
./fs/exportfs/expfs.c | 56 ++---------------------------------------------
./fs/jfs/jfs_inode.h | 2 -
./fs/jfs/namei.c | 32 ++++++++++++++++++++++++++
./fs/jfs/super.c | 1
./include/linux/efs_fs.h | 1
7 files changed, 71 insertions(+), 54 deletions(-)

diff .prev/fs/efs/namei.c ./fs/efs/namei.c
--- .prev/fs/efs/namei.c 2007-05-14 11:14:52.000000000 +1000
+++ ./fs/efs/namei.c 2007-05-14 11:15:29.000000000 +1000
@@ -75,6 +75,38 @@ struct dentry *efs_lookup(struct inode *
return NULL;
}

+struct dentry *efs_get_dentry(struct super_block *sb, void *vobjp)
+{
+ __u32 *objp = vobjp;
+ unsigned long ino = objp[0];
+ __u32 generation = objp[1];
+ 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)) {
+ result = ERR_PTR(-ESTALE);
+ goto out_iput;
+ }
+
+ result = d_alloc_anon(inode);
+ if (!result) {
+ result = ERR_PTR(-ENOMEM);
+ goto out_iput;
+ }
+ return result;
+
+ out_iput:
+ iput(inode);
+ return result;
+}
+
struct dentry *efs_get_parent(struct dentry *child)
{
struct dentry *parent;

diff .prev/fs/efs/super.c ./fs/efs/super.c
--- .prev/fs/efs/super.c 2007-05-14 11:15:23.000000000 +1000
+++ ./fs/efs/super.c 2007-05-14 11:15:29.000000000 +1000
@@ -115,6 +115,7 @@ static const struct super_operations efs
};

static struct export_operations efs_export_ops = {
+ .get_dentry = efs_get_dentry,
.get_parent = efs_get_parent,
};

diff .prev/fs/exportfs/expfs.c ./fs/exportfs/expfs.c
--- .prev/fs/exportfs/expfs.c 2007-05-14 11:15:23.000000000 +1000
+++ ./fs/exportfs/expfs.c 2007-05-14 11:15:29.000000000 +1000
@@ -391,61 +391,11 @@ out:
return error;
}

-
-static struct dentry *export_iget(struct super_block *sb, unsigned long ino, __u32 generation)
+static struct dentry *get_dentry(struct super_block *sb, void *vobjp)
{
-
- /* 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);
- }
- return result;
+ return ERR_PTR(-ESTALE);
}

-
-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
@@ -524,7 +474,7 @@ struct export_operations export_op_defau

.get_name = get_name,
.get_parent = get_parent,
- .get_dentry = get_object,
+ .get_dentry = get_dentry,
};

EXPORT_SYMBOL(export_op_default);

diff .prev/fs/jfs/jfs_inode.h ./fs/jfs/jfs_inode.h
--- .prev/fs/jfs/jfs_inode.h 2007-05-14 11:14:52.000000000 +1000
+++ ./fs/jfs/jfs_inode.h 2007-05-14 11:15:29.000000000 +1000
@@ -31,7 +31,7 @@ extern void jfs_truncate(struct inode *)
extern void jfs_truncate_nolock(struct inode *, loff_t);
extern void jfs_free_zero_link(struct inode *);
extern struct dentry *jfs_get_parent(struct dentry *dentry);
-extern void jfs_get_inode_flags(struct jfs_inode_info *);
+extern struct dentry *jfs_get_dentry(struct super_block *sb, void *vobjp);
extern void jfs_set_inode_flags(struct inode *);
extern int jfs_get_block(struct inode *, sector_t, struct buffer_head *, int);

diff .prev/fs/jfs/namei.c ./fs/jfs/namei.c
--- .prev/fs/jfs/namei.c 2007-05-14 11:14:52.000000000 +1000
+++ ./fs/jfs/namei.c 2007-05-14 11:15:29.000000000 +1000
@@ -1477,6 +1477,38 @@ static struct dentry *jfs_lookup(struct
return dentry;
}

+struct dentry *jfs_get_dentry(struct super_block *sb, void *vobjp)
+{
+ __u32 *objp = vobjp;
+ unsigned long ino = objp[0];
+ __u32 generation = objp[1];
+ 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)) {
+ result = ERR_PTR(-ESTALE);
+ goto out_iput;
+ }
+
+ result = d_alloc_anon(inode);
+ if (!result) {
+ result = ERR_PTR(-ENOMEM);
+ goto out_iput;
+ }
+ return result;
+
+ out_iput:
+ iput(inode);
+ return result;
+}
+
struct dentry *jfs_get_parent(struct dentry *dentry)
{
struct super_block *sb = dentry->d_inode->i_sb;

diff .prev/fs/jfs/super.c ./fs/jfs/super.c
--- .prev/fs/jfs/super.c 2007-05-14 11:15:23.000000000 +1000
+++ ./fs/jfs/super.c 2007-05-14 11:15:29.000000000 +1000
@@ -738,6 +738,7 @@ static const struct super_operations jfs
};

static struct export_operations jfs_export_operations = {
+ .get_dentry = jfs_get_dentry,
.get_parent = jfs_get_parent,
};

diff .prev/include/linux/efs_fs.h ./include/linux/efs_fs.h
--- .prev/include/linux/efs_fs.h 2007-05-14 11:14:52.000000000 +1000
+++ ./include/linux/efs_fs.h 2007-05-14 11:15:29.000000000 +1000
@@ -45,6 +45,7 @@ extern efs_block_t efs_map_block(struct
extern int efs_get_block(struct inode *, sector_t, struct buffer_head *, int);

extern struct dentry *efs_lookup(struct inode *, struct dentry *, struct nameidata *);
+extern struct dentry *efs_get_dentry(struct super_block *sb, void *vobjp);
extern struct dentry *efs_get_parent(struct dentry *);
extern int efs_bmap(struct inode *, int);