diff options
| -rw-r--r-- | fs/exportfs/expfs.c | 136 | ||||
| -rw-r--r-- | fs/libfs.c | 88 | ||||
| -rw-r--r-- | include/linux/exportfs.h | 30 |
3 files changed, 248 insertions, 6 deletions
diff --git a/fs/exportfs/expfs.c b/fs/exportfs/expfs.c index 813011aad700..99294a23cd54 100644 --- a/fs/exportfs/expfs.c +++ b/fs/exportfs/expfs.c @@ -514,17 +514,141 @@ struct dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid, int (*acceptable)(void *, struct dentry *), void *context) { struct export_operations *nop = mnt->mnt_sb->s_export_op; - struct dentry *result; + struct dentry *result, *alias; + int err; - if (nop->decode_fh) { - result = nop->decode_fh(mnt->mnt_sb, fid->raw, fh_len, + /* + * Old way of doing things. Will go away soon. + */ + if (!nop->fh_to_dentry) { + if (nop->decode_fh) { + return nop->decode_fh(mnt->mnt_sb, fid->raw, fh_len, fileid_type, acceptable, context); + } else { + return export_decode_fh(mnt->mnt_sb, fid->raw, fh_len, + fileid_type, acceptable, context); + } + } + + /* + * Try to get any dentry for the given file handle from the filesystem. + */ + result = nop->fh_to_dentry(mnt->mnt_sb, fid, fh_len, fileid_type); + if (!result) + result = ERR_PTR(-ESTALE); + if (IS_ERR(result)) + return result; + + if (S_ISDIR(result->d_inode->i_mode)) { + /* + * This request is for a directory. + * + * On the positive side there is only one dentry for each + * directory inode. On the negative side this implies that we + * to ensure our dentry is connected all the way up to the + * filesystem root. + */ + if (result->d_flags & DCACHE_DISCONNECTED) { + err = reconnect_path(mnt->mnt_sb, result); + if (err) + goto err_result; + } + + if (!acceptable(context, result)) { + err = -EACCES; + goto err_result; + } + + return result; } else { - result = export_decode_fh(mnt->mnt_sb, fid->raw, fh_len, - fileid_type, acceptable, context); + /* + * It's not a directory. Life is a little more complicated. + */ + struct dentry *target_dir, *nresult; + char nbuf[NAME_MAX+1]; + + /* + * See if either the dentry we just got from the filesystem + * or any alias for it is acceptable. This is always true + * if this filesystem is exported without the subtreecheck + * option. If the filesystem is exported with the subtree + * check option there's a fair chance we need to look at + * the parent directory in the file handle and make sure + * it's connected to the filesystem root. + */ + alias = find_acceptable_alias(result, acceptable, context); + if (alias) + return alias; + + /* + * Try to extract a dentry for the parent directory from the + * file handle. If this fails we'll have to give up. + */ + err = -ESTALE; + if (!nop->fh_to_parent) + goto err_result; + + target_dir = nop->fh_to_parent(mnt->mnt_sb, fid, + fh_len, fileid_type); + if (!target_dir) + goto err_result; + err = PTR_ERR(target_dir); + if (IS_ERR(target_dir)) + goto err_result; + + /* + * And as usual we need to make sure the parent directory is + * connected to the filesystem root. The VFS really doesn't + * like disconnected directories.. + */ + err = reconnect_path(mnt->mnt_sb, target_dir); + if (err) { + dput(target_dir); + goto err_result; + } + + /* + * Now that we've got both a well-connected parent and a + * dentry for the inode we're after, make sure that our + * inode is actually connected to the parent. + */ + err = exportfs_get_name(target_dir, nbuf, result); + if (!err) { + mutex_lock(&target_dir->d_inode->i_mutex); + nresult = lookup_one_len(nbuf, target_dir, + strlen(nbuf)); + mutex_unlock(&target_dir->d_inode->i_mutex); + if (!IS_ERR(nresult)) { + if (nresult->d_inode) { + dput(result); + result = nresult; + } else + dput(nresult); + } + } + + /* + * At this point we are done with the parent, but it's pinned + * by the child dentry anyway. + */ + dput(target_dir); + + /* + * And finally make sure the dentry is actually acceptable + * to NFSD. + */ + alias = find_acceptable_alias(result, acceptable, context); + if (!alias) { + err = -EACCES; + goto err_result; + } + + return alias; } - return result; + err_result: + dput(result); + return ERR_PTR(err); } EXPORT_SYMBOL_GPL(exportfs_decode_fh); diff --git a/fs/libfs.c b/fs/libfs.c index ae51481e45e5..6e68b700958d 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -8,6 +8,7 @@ #include <linux/mount.h> #include <linux/vfs.h> #include <linux/mutex.h> +#include <linux/exportfs.h> #include <asm/uaccess.h> @@ -678,6 +679,93 @@ out: return ret; } +/* + * This is what d_alloc_anon should have been. Once the exportfs + * argument transition has been finished I will update d_alloc_anon + * to this prototype and this wrapper will go away. --hch + */ +static struct dentry *exportfs_d_alloc(struct inode *inode) +{ + struct dentry *dentry; + + if (!inode) + return NULL; + if (IS_ERR(inode)) + return ERR_PTR(PTR_ERR(inode)); + + dentry = d_alloc_anon(inode); + if (!dentry) { + iput(inode); + dentry = ERR_PTR(-ENOMEM); + } + return dentry; +} + +/** + * generic_fh_to_dentry - generic helper for the fh_to_dentry export operation + * @sb: filesystem to do the file handle conversion on + * @fid: file handle to convert + * @fh_len: length of the file handle in bytes + * @fh_type: type of file handle + * @get_inode: filesystem callback to retrieve inode + * + * This function decodes @fid as long as it has one of the well-known + * Linux filehandle types and calls @get_inode on it to retrieve the + * inode for the object specified in the file handle. + */ +struct dentry *generic_fh_to_dentry(struct super_block *sb, struct fid *fid, + int fh_len, int fh_type, struct inode *(*get_inode) + (struct super_block *sb, u64 ino, u32 gen)) +{ + struct inode *inode = NULL; + + if (fh_len < 2) + return NULL; + + switch (fh_type) { + case FILEID_INO32_GEN: + case FILEID_INO32_GEN_PARENT: + inode = get_inode(sb, fid->i32.ino, fid->i32.gen); + break; + } + + return exportfs_d_alloc(inode); +} +EXPORT_SYMBOL_GPL(generic_fh_to_dentry); + +/** + * generic_fh_to_dentry - generic helper for the fh_to_parent export operation + * @sb: filesystem to do the file handle conversion on + * @fid: file handle to convert + * @fh_len: length of the file handle in bytes + * @fh_type: type of file handle + * @get_inode: filesystem callback to retrieve inode + * + * This function decodes @fid as long as it has one of the well-known + * Linux filehandle types and calls @get_inode on it to retrieve the + * inode for the _parent_ object specified in the file handle if it + * is specified in the file handle, or NULL otherwise. + */ +struct dentry *generic_fh_to_parent(struct super_block *sb, struct fid *fid, + int fh_len, int fh_type, struct inode *(*get_inode) + (struct super_block *sb, u64 ino, u32 gen)) +{ + struct inode *inode = NULL; + + if (fh_len <= 2) + return NULL; + + switch (fh_type) { + case FILEID_INO32_GEN_PARENT: + inode = get_inode(sb, fid->i32.parent_ino, + (fh_len > 3 ? fid->i32.parent_gen : 0)); + break; + } + + return exportfs_d_alloc(inode); +} +EXPORT_SYMBOL_GPL(generic_fh_to_parent); + EXPORT_SYMBOL(dcache_dir_close); EXPORT_SYMBOL(dcache_dir_lseek); EXPORT_SYMBOL(dcache_dir_open); diff --git a/include/linux/exportfs.h b/include/linux/exportfs.h index 06178a1336ff..b44f6b6871c8 100644 --- a/include/linux/exportfs.h +++ b/include/linux/exportfs.h @@ -4,6 +4,7 @@ #include <linux/types.h> struct dentry; +struct inode; struct super_block; struct vfsmount; @@ -101,6 +102,21 @@ struct fid { * the filehandle fragment. encode_fh() should return the number of bytes * stored or a negative error code such as %-ENOSPC * + * fh_to_dentry: + * @fh_to_dentry is given a &struct super_block (@sb) and a file handle + * fragment (@fh, @fh_len). It should return a &struct dentry which refers + * to the same file that the file handle fragment refers to. If it cannot, + * it should return a %NULL pointer if the file was found but no acceptable + * &dentries were available, or an %ERR_PTR error code indicating why it + * couldn't be found (e.g. %ENOENT or %ENOMEM). Any suitable dentry can be + * returned including, if necessary, a new dentry created with d_alloc_root. + * The caller can then find any other extant dentries by following the + * d_alias links. + * + * fh_to_parent: + * Same as @fh_to_dentry, except that it returns a pointer to the parent + * dentry if it was encoded into the filehandle fragment by @encode_fh. + * * get_name: * @get_name should find a name for the given @child in the given @parent * directory. The name should be stored in the @name (with the @@ -139,6 +155,10 @@ struct export_operations { void *context); int (*encode_fh)(struct dentry *de, __u32 *fh, int *max_len, int connectable); + struct dentry * (*fh_to_dentry)(struct super_block *sb, struct fid *fid, + int fh_len, int fh_type); + struct dentry * (*fh_to_parent)(struct super_block *sb, struct fid *fid, + int fh_len, int fh_type); int (*get_name)(struct dentry *parent, char *name, struct dentry *child); struct dentry * (*get_parent)(struct dentry *child); @@ -161,4 +181,14 @@ extern struct dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid, int fh_len, int fileid_type, int (*acceptable)(void *, struct dentry *), void *context); +/* + * Generic helpers for filesystems. + */ +extern struct dentry *generic_fh_to_dentry(struct super_block *sb, + struct fid *fid, int fh_len, int fh_type, + struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen)); +extern struct dentry *generic_fh_to_parent(struct super_block *sb, + struct fid *fid, int fh_len, int fh_type, + struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen)); + #endif /* LINUX_EXPORTFS_H */ |