diff options
Diffstat (limited to 'fs/isofs/export.c')
| -rw-r--r-- | fs/isofs/export.c | 228 |
1 files changed, 228 insertions, 0 deletions
diff --git a/fs/isofs/export.c b/fs/isofs/export.c new file mode 100644 index 000000000000..e4252c960871 --- /dev/null +++ b/fs/isofs/export.c @@ -0,0 +1,228 @@ +/* + * fs/isofs/export.c + * + * (C) 2004 Paul Serice - The new inode scheme requires switching + * from iget() to iget5_locked() which means + * the NFS export operations have to be hand + * coded because the default routines rely on + * iget(). + * + * The following files are helpful: + * + * Documentation/filesystems/Exporting + * fs/exportfs/expfs.c. + */ + +#include <linux/buffer_head.h> +#include <linux/errno.h> +#include <linux/fs.h> +#include <linux/iso_fs.h> +#include <linux/kernel.h> + +static struct dentry * +isofs_export_iget(struct super_block *sb, + unsigned long block, + unsigned long offset, + __u32 generation) +{ + struct inode *inode; + struct dentry *result; + if (block == 0) + return ERR_PTR(-ESTALE); + inode = isofs_iget(sb, block, offset); + if (inode == NULL) + return ERR_PTR(-ENOMEM); + if (is_bad_inode(inode) + || (generation && inode->i_generation != generation)) + { + iput(inode); + return ERR_PTR(-ESTALE); + } + result = d_alloc_anon(inode); + if (!result) { + iput(inode); + return ERR_PTR(-ENOMEM); + } + return result; +} + +static struct dentry * +isofs_export_get_dentry(struct super_block *sb, void *vobjp) +{ + __u32 *objp = vobjp; + unsigned long block = objp[0]; + unsigned long offset = objp[1]; + __u32 generation = objp[2]; + return isofs_export_iget(sb, block, offset, generation); +} + +/* This function is surprisingly simple. The trick is understanding + * that "child" is always a directory. So, to find its parent, you + * simply need to find its ".." entry, normalize its block and offset, + * and return the underlying inode. See the comments for + * isofs_normalize_block_and_offset(). */ +static struct dentry *isofs_export_get_parent(struct dentry *child) +{ + unsigned long parent_block = 0; + unsigned long parent_offset = 0; + struct inode *child_inode = child->d_inode; + struct iso_inode_info *e_child_inode = ISOFS_I(child_inode); + struct inode *parent_inode = NULL; + struct iso_directory_record *de = NULL; + struct buffer_head * bh = NULL; + struct dentry *rv = NULL; + + /* "child" must always be a directory. */ + if (!S_ISDIR(child_inode->i_mode)) { + printk(KERN_ERR "isofs: isofs_export_get_parent(): " + "child is not a directory!\n"); + rv = ERR_PTR(-EACCES); + goto out; + } + + /* It is an invariant that the directory offset is zero. If + * it is not zero, it means the directory failed to be + * normalized for some reason. */ + if (e_child_inode->i_iget5_offset != 0) { + printk(KERN_ERR "isofs: isofs_export_get_parent(): " + "child directory not normalized!\n"); + rv = ERR_PTR(-EACCES); + goto out; + } + + /* The child inode has been normalized such that its + * i_iget5_block value points to the "." entry. Fortunately, + * the ".." entry is located in the same block. */ + parent_block = e_child_inode->i_iget5_block; + + /* Get the block in question. */ + bh = sb_bread(child_inode->i_sb, parent_block); + if (bh == NULL) { + rv = ERR_PTR(-EACCES); + goto out; + } + + /* This is the "." entry. */ + de = (struct iso_directory_record*)bh->b_data; + + /* The ".." entry is always the second entry. */ + parent_offset = (unsigned long)isonum_711(de->length); + de = (struct iso_directory_record*)(bh->b_data + parent_offset); + + /* Verify it is in fact the ".." entry. */ + if ((isonum_711(de->name_len) != 1) || (de->name[0] != 1)) { + printk(KERN_ERR "isofs: Unable to find the \"..\" " + "directory for NFS.\n"); + rv = ERR_PTR(-EACCES); + goto out; + } + + /* Normalize */ + isofs_normalize_block_and_offset(de, &parent_block, &parent_offset); + + /* Get the inode. */ + parent_inode = isofs_iget(child_inode->i_sb, + parent_block, + parent_offset); + if (parent_inode == NULL) { + rv = ERR_PTR(-EACCES); + goto out; + } + + /* Allocate the dentry. */ + rv = d_alloc_anon(parent_inode); + if (rv == NULL) { + rv = ERR_PTR(-ENOMEM); + goto out; + } + + out: + if (bh) { + brelse(bh); + } + return rv; +} + +static int +isofs_export_encode_fh(struct dentry *dentry, + __u32 *fh32, + int *max_len, + int connectable) +{ + struct inode * inode = dentry->d_inode; + struct iso_inode_info * ei = ISOFS_I(inode); + int len = *max_len; + int type = 1; + __u16 *fh16 = (__u16*)fh32; + + /* + * WARNING: max_len is 5 for NFSv2. Because of this + * limitation, we use the lower 16 bits of fh32[1] to hold the + * offset of the inode and the upper 16 bits of fh32[1] to + * hold the offset of the parent. + */ + + if (len < 3 || (connectable && len < 5)) + return 255; + + len = 3; + fh32[0] = ei->i_iget5_block; + fh16[2] = (__u16)ei->i_iget5_offset; /* fh16 [sic] */ + fh32[2] = inode->i_generation; + if (connectable && !S_ISDIR(inode->i_mode)) { + struct inode *parent; + struct iso_inode_info *eparent; + spin_lock(&dentry->d_lock); + parent = dentry->d_parent->d_inode; + eparent = ISOFS_I(parent); + fh32[3] = eparent->i_iget5_block; + fh16[3] = (__u16)eparent->i_iget5_offset; /* fh16 [sic] */ + fh32[4] = parent->i_generation; + spin_unlock(&dentry->d_lock); + len = 5; + type = 2; + } + *max_len = len; + return type; +} + + +static struct dentry * +isofs_export_decode_fh(struct super_block *sb, + __u32 *fh32, + int fh_len, + int fileid_type, + int (*acceptable)(void *context, struct dentry *de), + void *context) +{ + __u16 *fh16 = (__u16*)fh32; + __u32 child[3]; /* The child is what triggered all this. */ + __u32 parent[3]; /* The parent is just along for the ride. */ + + if (fh_len < 3 || fileid_type > 2) + return NULL; + + child[0] = fh32[0]; + child[1] = fh16[2]; /* fh16 [sic] */ + child[2] = fh32[2]; + + parent[0] = 0; + parent[1] = 0; + parent[2] = 0; + if (fileid_type == 2) { + if (fh_len > 2) parent[0] = fh32[3]; + parent[1] = fh16[3]; /* fh16 [sic] */ + if (fh_len > 4) parent[2] = fh32[4]; + } + + return sb->s_export_op->find_exported_dentry(sb, child, parent, + acceptable, context); +} + + +struct export_operations isofs_export_ops = { + .decode_fh = isofs_export_decode_fh, + .encode_fh = isofs_export_encode_fh, + .get_dentry = isofs_export_get_dentry, + .get_parent = isofs_export_get_parent, +}; |