nfsd: last_byte_offset

refactor the nfs4 server lock code to use last_byte_offset
to compute the last byte covered by the lock.  Check for overflow
so that the last byte is set to NFS4_MAX_UINT64 if offset + len
wraps around.

Also, use NFS4_MAX_UINT64 for ~(u64)0 where appropriate.

Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

1 files changed, 26 insertions, 16 deletions

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index e62d0e3df8b3..88db7d3ec120 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -2416,6 +2416,26 @@ out:
 #define LOCK_HASH_SIZE             (1 << LOCK_HASH_BITS)
 #define LOCK_HASH_MASK             (LOCK_HASH_SIZE - 1)
 
+static inline u64
+end_offset(u64 start, u64 len)
+{
+        u64 end;
+
+        end = start + len;
+        return end >= start ? end: NFS4_MAX_UINT64;
+}
+
+/* last octet in a range */
+static inline u64
+last_byte_offset(u64 start, u64 len)
+{
+        u64 end;
+
+        BUG_ON(!len);
+        end = start + len;
+        return end > start ? end - 1: NFS4_MAX_UINT64;
+}
+
 #define lockownerid_hashval(id) \
         ((id) & LOCK_HASH_MASK)
 
@@ -2519,8 +2539,8 @@ nfs4_set_lock_denied(struct file_lock *fl, struct nfsd4_lock_denied *deny)
                 deny->ld_clientid.cl_id = 0;
         }
         deny->ld_start = fl->fl_start;
-        deny->ld_length = ~(u64)0;
-        if (fl->fl_end != ~(u64)0)
+        deny->ld_length = NFS4_MAX_UINT64;
+        if (fl->fl_end != NFS4_MAX_UINT64)
                 deny->ld_length = fl->fl_end - fl->fl_start + 1;        
         deny->ld_type = NFS4_READ_LT;
         if (fl->fl_type != F_RDLCK)
@@ -2617,7 +2637,7 @@ out:
 static int
 check_lock_length(u64 offset, u64 length)
 {
-        return ((length == 0)  || ((length != ~(u64)0) &&
+        return ((length == 0)  || ((length != NFS4_MAX_UINT64) &&
              LOFF_OVERFLOW(offset, length)));
 }
 
@@ -2737,11 +2757,7 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
         file_lock.fl_lmops = &nfsd_posix_mng_ops;
 
         file_lock.fl_start = lock->lk_offset;
-        if ((lock->lk_length == ~(u64)0) || 
-                        LOFF_OVERFLOW(lock->lk_offset, lock->lk_length))
-                file_lock.fl_end = ~(u64)0;
-        else
-                file_lock.fl_end = lock->lk_offset + lock->lk_length - 1;
+        file_lock.fl_end = last_byte_offset(lock->lk_offset, lock->lk_length);
         nfs4_transform_lock_offset(&file_lock);
 
         /*
@@ -2858,10 +2874,7 @@ nfsd4_lockt(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
         file_lock.fl_lmops = &nfsd_posix_mng_ops;
 
         file_lock.fl_start = lockt->lt_offset;
-        if ((lockt->lt_length == ~(u64)0) || LOFF_OVERFLOW(lockt->lt_offset, lockt->lt_length))
-                file_lock.fl_end = ~(u64)0;
-        else
-                file_lock.fl_end = lockt->lt_offset + lockt->lt_length - 1;
+        file_lock.fl_end = last_byte_offset(lockt->lt_offset, lockt->lt_length);
 
         nfs4_transform_lock_offset(&file_lock);
 
@@ -2917,10 +2930,7 @@ nfsd4_locku(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
         file_lock.fl_lmops = &nfsd_posix_mng_ops;
         file_lock.fl_start = locku->lu_offset;
 
-        if ((locku->lu_length == ~(u64)0) || LOFF_OVERFLOW(locku->lu_offset, locku->lu_length))
-                file_lock.fl_end = ~(u64)0;
-        else
-                file_lock.fl_end = locku->lu_offset + locku->lu_length - 1;
+        file_lock.fl_end = last_byte_offset(locku->lu_offset, locku->lu_length);
         nfs4_transform_lock_offset(&file_lock);
 
         /*