exportfs: Return the minimum required handle size

The exportfs encode handle function should return the minimum required
handle size. This helps user to find out the handle size by passing 0
handle size in the first step and then redoing to the call again with
the returned handle size value.

Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/btrfs/export.c b/fs/btrfs/export.c
index ff27d7a..b4ffad8 100644 (file)
--- a/fs/btrfs/export.c
+++ b/fs/btrfs/export.c
@@ -21,9 +21,13 @@ static int btrfs_encode_fh(struct dentry *dentry, u32 *fh, int *max_len,
        int len = *max_len;
        int type;
 
-       if ((len < BTRFS_FID_SIZE_NON_CONNECTABLE) ||
-           (connectable && len < BTRFS_FID_SIZE_CONNECTABLE))
+       if (connectable && (len < BTRFS_FID_SIZE_CONNECTABLE)) {
+               *max_len = BTRFS_FID_SIZE_CONNECTABLE;
                return 255;
+       } else if (len < BTRFS_FID_SIZE_NON_CONNECTABLE) {
+               *max_len = BTRFS_FID_SIZE_NON_CONNECTABLE;
+               return 255;
+       }
 
        len  = BTRFS_FID_SIZE_NON_CONNECTABLE;
        type = FILEID_BTRFS_WITHOUT_PARENT;

diff --git a/fs/exportfs/expfs.c b/fs/exportfs/expfs.c
index 4b68257..cfe5573 100644 (file)
--- a/fs/exportfs/expfs.c
+++ b/fs/exportfs/expfs.c
@@ -320,9 +320,14 @@ static int export_encode_fh(struct dentry *dentry, struct fid *fid,
        struct inode * inode = dentry->d_inode;
        int len = *max_len;
        int type = FILEID_INO32_GEN;
-       
-       if (len < 2 || (connectable && len < 4))
+
+       if (connectable && (len < 4)) {
+               *max_len = 4;
+               return 255;
+       } else if (len < 2) {
+               *max_len = 2;
                return 255;
+       }
 
        len = 2;
        fid->i32.ino = inode->i_ino;

diff --git a/fs/fat/inode.c b/fs/fat/inode.c
index 86753fe..0e277ec 100644 (file)
--- a/fs/fat/inode.c
+++ b/fs/fat/inode.c
@@ -757,8 +757,10 @@ fat_encode_fh(struct dentry *de, __u32 *fh, int *lenp, int connectable)
        struct inode *inode =  de->d_inode;
        u32 ipos_h, ipos_m, ipos_l;
 
-       if (len < 5)
+       if (len < 5) {
+               *lenp = 5;
                return 255; /* no room */
+       }
 
        ipos_h = MSDOS_I(inode)->i_pos >> 8;
        ipos_m = (MSDOS_I(inode)->i_pos & 0xf0) << 24;

diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 9e3f68c..051b1a0 100644 (file)
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -637,8 +637,10 @@ static int fuse_encode_fh(struct dentry *dentry, u32 *fh, int *max_len,
        u64 nodeid;
        u32 generation;
 
-       if (*max_len < len)
+       if (*max_len < len) {
+               *max_len = len;
                return  255;
+       }
 
        nodeid = get_fuse_inode(inode)->nodeid;
        generation = inode->i_generation;

diff --git a/fs/gfs2/export.c b/fs/gfs2/export.c
index 9023db8..b5a5e60 100644 (file)
--- a/fs/gfs2/export.c
+++ b/fs/gfs2/export.c
@@ -36,9 +36,13 @@ static int gfs2_encode_fh(struct dentry *dentry, __u32 *p, int *len,
        struct super_block *sb = inode->i_sb;
        struct gfs2_inode *ip = GFS2_I(inode);
 
-       if (*len < GFS2_SMALL_FH_SIZE ||
-           (connectable && *len < GFS2_LARGE_FH_SIZE))
+       if (connectable && (*len < GFS2_LARGE_FH_SIZE)) {
+               *len = GFS2_LARGE_FH_SIZE;
                return 255;
+       } else if (*len < GFS2_SMALL_FH_SIZE) {
+               *len = GFS2_SMALL_FH_SIZE;
+               return 255;
+       }
 
        fh[0] = cpu_to_be32(ip->i_no_formal_ino >> 32);
        fh[1] = cpu_to_be32(ip->i_no_formal_ino & 0xFFFFFFFF);

diff --git a/fs/isofs/export.c b/fs/isofs/export.c
index ed752cb..dd4687f 100644 (file)
--- a/fs/isofs/export.c
+++ b/fs/isofs/export.c
@@ -124,9 +124,13 @@ isofs_export_encode_fh(struct dentry *dentry,
         * 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))
+       if (connectable && (len < 5)) {
+               *max_len = 5;
+               return 255;
+       } else if (len < 3) {
+               *max_len = 3;
                return 255;
+       }
 
        len = 3;
        fh32[0] = ei->i_iget5_block;

diff --git a/fs/ocfs2/export.c b/fs/ocfs2/export.c
index 5dbc306..254652a 100644 (file)
--- a/fs/ocfs2/export.c
+++ b/fs/ocfs2/export.c
@@ -197,8 +197,12 @@ static int ocfs2_encode_fh(struct dentry *dentry, u32 *fh_in, int *max_len,
                   dentry->d_name.len, dentry->d_name.name,
                   fh, len, connectable);
 
-       if (len < 3 || (connectable && len < 6)) {
-               mlog(ML_ERROR, "fh buffer is too small for encoding\n");
+       if (connectable && (len < 6)) {
+               *max_len = 6;
+               type = 255;
+               goto bail;
+       } else if (len < 3) {
+               *max_len = 3;
                type = 255;
                goto bail;
        }

diff --git a/fs/reiserfs/inode.c b/fs/reiserfs/inode.c
index 0bae036..1bba24b 100644 (file)
--- a/fs/reiserfs/inode.c
+++ b/fs/reiserfs/inode.c
@@ -1593,8 +1593,13 @@ int reiserfs_encode_fh(struct dentry *dentry, __u32 * data, int *lenp,
        struct inode *inode = dentry->d_inode;
        int maxlen = *lenp;
 
-       if (maxlen < 3)
+       if (need_parent && (maxlen < 5)) {
+               *lenp = 5;
                return 255;
+       } else if (maxlen < 3) {
+               *lenp = 3;
+               return 255;
+       }
 
        data[0] = inode->i_ino;
        data[1] = le32_to_cpu(INODE_PKEY(inode)->k_dir_id);

diff --git a/fs/udf/namei.c b/fs/udf/namei.c
index b7c338d..f1dce84 100644 (file)
--- a/fs/udf/namei.c
+++ b/fs/udf/namei.c
@@ -1286,8 +1286,13 @@ static int udf_encode_fh(struct dentry *de, __u32 *fh, int *lenp,
        struct fid *fid = (struct fid *)fh;
        int type = FILEID_UDF_WITHOUT_PARENT;
 
-       if (len < 3 || (connectable && len < 5))
+       if (connectable && (len < 5)) {
+               *lenp = 5;
+               return 255;
+       } else if (len < 3) {
+               *lenp = 3;
                return 255;
+       }
 
        *lenp = 3;
        fid->udf.block = location.logicalBlockNum;

diff --git a/fs/xfs/linux-2.6/xfs_export.c b/fs/xfs/linux-2.6/xfs_export.c
index fc0114d..f4f878f 100644 (file)
--- a/fs/xfs/linux-2.6/xfs_export.c
+++ b/fs/xfs/linux-2.6/xfs_export.c
@@ -89,8 +89,10 @@ xfs_fs_encode_fh(
         * seven combinations work.  The real answer is "don't use v2".
         */
        len = xfs_fileid_length(fileid_type);
-       if (*max_len < len)
+       if (*max_len < len) {
+               *max_len = len;
                return 255;
+       }
        *max_len = len;
 
        switch (fileid_type) {

diff --git a/include/linux/exportfs.h b/include/linux/exportfs.h
index 2802898..65afdfd 100644 (file)
--- a/include/linux/exportfs.h
+++ b/include/linux/exportfs.h
@@ -121,8 +121,10 @@ struct fid {
  *    set, the encode_fh() should store sufficient information so that a good
  *    attempt can be made to find not only the file but also it's place in the
  *    filesystem.   This typically means storing a reference to de->d_parent in
- *    the filehandle fragment.  encode_fh() should return the number of bytes
- *    stored or a negative error code such as %-ENOSPC
+ *    the filehandle fragment.  encode_fh() should return the fileid_type on
+ *    success and on error returns 255 (if the space needed to encode fh is
+ *    greater than @max_len*4 bytes). On error @max_len contains the minimum
+ *    size(in 4 byte unit) needed to encode the file handle.
  *
  * fh_to_dentry:
  *    @fh_to_dentry is given a &struct super_block (@sb) and a file handle

diff --git a/mm/shmem.c b/mm/shmem.c
index 5ee67c9..3437b65 100644 (file)
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -2144,8 +2144,10 @@ static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len,
 {
        struct inode *inode = dentry->d_inode;
 
-       if (*len < 3)
+       if (*len < 3) {
+               *len = 3;
                return 255;
+       }
 
        if (inode_unhashed(inode)) {
                /* Unfortunately insert_inode_hash is not idempotent,