NFS: Reduce time spent holding the i_mutex during fallocate()

At the very least, we should not be taking the i_mutex until after
checking if the server even supports ALLOCATE or DEALLOCATE, allowing
v4.0 or v4.1 to exit without potentially waiting on a lock.

Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

2 files changed, 10 insertions, 7 deletions

diff --git a/fs/nfs/nfs42proc.c b/fs/nfs/nfs42proc.c
index b9aa6bbcc8ed..3a9e75235f30 100644
--- a/fs/nfs/nfs42proc.c
+++ b/fs/nfs/nfs42proc.c
@@ -96,9 +96,13 @@ int nfs42_proc_allocate(struct file *filep, loff_t offset, loff_t len)
         if (!nfs_server_capable(inode, NFS_CAP_ALLOCATE))
                 return -EOPNOTSUPP;
 
+        mutex_lock(&inode->i_mutex);
+
         err = nfs42_proc_fallocate(&msg, filep, offset, len);
         if (err == -EOPNOTSUPP)
                 NFS_SERVER(inode)->caps &= ~NFS_CAP_ALLOCATE;
+
+        mutex_unlock(&inode->i_mutex);
         return err;
 }
 
@@ -114,11 +118,15 @@ int nfs42_proc_deallocate(struct file *filep, loff_t offset, loff_t len)
                 return -EOPNOTSUPP;
 
         nfs_wb_all(inode);
+        mutex_lock(&inode->i_mutex);
+
         err = nfs42_proc_fallocate(&msg, filep, offset, len);
         if (err == 0)
                 truncate_pagecache_range(inode, offset, (offset + len) -1);
         if (err == -EOPNOTSUPP)
                 NFS_SERVER(inode)->caps &= ~NFS_CAP_DEALLOCATE;
+
+        mutex_unlock(&inode->i_mutex);
         return err;
 }
 
diff --git a/fs/nfs/nfs4file.c b/fs/nfs/nfs4file.c
index 151ddff624d4..cb3c7879e59f 100644
--- a/fs/nfs/nfs4file.c
+++ b/fs/nfs/nfs4file.c
@@ -158,14 +158,9 @@ static long nfs42_fallocate(struct file *filep, int mode, loff_t offset, loff_t
         if (ret < 0)
                 return ret;
 
-        mutex_lock(&inode->i_mutex);
         if (mode & FALLOC_FL_PUNCH_HOLE)
-                ret = nfs42_proc_deallocate(filep, offset, len);
-        else
-                ret = nfs42_proc_allocate(filep, offset, len);
-        mutex_unlock(&inode->i_mutex);
-
-        return ret;
+                return nfs42_proc_deallocate(filep, offset, len);
+        return nfs42_proc_allocate(filep, offset, len);
 }
 #endif /* CONFIG_NFS_V4_2 */