nfsd: Prevent truncation of an unlinked inode from blocking access to its directory

Truncation of an unlinked inode may take a long time for I/O waiting, and
it doesn't have to prevent access to the directory. Thus, let truncation
occur outside the directory's mutex, just like do_unlinkat() does.

Signed-off-by: Yu Hsiang Huang <nickhuang@synology.com>
Signed-off-by: Bing Jing Chang <bingjingc@synology.com>
Signed-off-by: Robbie Ko <robbieko@synology.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 15adf1f..39948f1 100644 (file)
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -1859,6 +1859,7 @@ nfsd_unlink(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
 {
        struct dentry   *dentry, *rdentry;
        struct inode    *dirp;
+       struct inode    *rinode;
        __be32          err;
        int             host_err;
 
@@ -1887,6 +1888,8 @@ nfsd_unlink(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
                host_err = -ENOENT;
                goto out_drop_write;
        }
+       rinode = d_inode(rdentry);
+       ihold(rinode);
 
        if (!type)
                type = d_inode(rdentry)->i_mode & S_IFMT;
@@ -1902,6 +1905,8 @@ nfsd_unlink(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
        if (!host_err)
                host_err = commit_metadata(fhp);
        dput(rdentry);
+       fh_unlock(fhp);
+       iput(rinode);    /* truncate the inode here */
 
 out_drop_write:
        fh_drop_write(fhp);