NFSv4.2/pnfs: Use GFP_NOIO for layoutstat reporting in the writeback path

Prevent a potential deadlock.
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

fs/nfs/flexfilelayout/flexfilelayout.c

@@ -510,7 +510,8 @@ nfs4_ff_layout_stat_io_start_read(struct nfs4_ff_layout_mirror *mirror,
 	spin_unlock(&mirror->lock);
 
 	if (report)
-		pnfs_report_layoutstat(mirror->lseg->pls_layout->plh_inode);
+		pnfs_report_layoutstat(mirror->lseg->pls_layout->plh_inode,
+				GFP_KERNEL);
 }
 
 static void
@@ -538,7 +539,8 @@ nfs4_ff_layout_stat_io_start_write(struct nfs4_ff_layout_mirror *mirror,
 	spin_unlock(&mirror->lock);
 
 	if (report)
-		pnfs_report_layoutstat(mirror->lseg->pls_layout->plh_inode);
+		pnfs_report_layoutstat(mirror->lseg->pls_layout->plh_inode,
+				GFP_NOIO);
 }
 
 static void

fs/nfs/pnfs.c

@@ -2267,7 +2267,7 @@ struct nfs4_threshold *pnfs_mdsthreshold_alloc(void)
 
 #if IS_ENABLED(CONFIG_NFS_V4_2)
 int
-pnfs_report_layoutstat(struct inode *inode)
+pnfs_report_layoutstat(struct inode *inode, gfp_t gfp_flags)
 {
 	struct pnfs_layoutdriver_type *ld = NFS_SERVER(inode)->pnfs_curr_ld;
 	struct nfs_server *server = NFS_SERVER(inode);
@@ -2294,7 +2294,7 @@ pnfs_report_layoutstat(struct inode *inode)
 	pnfs_get_layout_hdr(hdr);
 	spin_unlock(&inode->i_lock);
 
-	data = kzalloc(sizeof(*data), GFP_KERNEL);
+	data = kzalloc(sizeof(*data), gfp_flags);
 	if (!data) {
 		status = -ENOMEM;
 		goto out_put;

fs/nfs/pnfs.h

@@ -691,10 +691,10 @@ static inline void nfs4_pnfs_v3_ds_connect_unload(void)
 #endif /* CONFIG_NFS_V4_1 */
 
 #if IS_ENABLED(CONFIG_NFS_V4_2)
-int pnfs_report_layoutstat(struct inode *inode);
+int pnfs_report_layoutstat(struct inode *inode, gfp_t gfp_flags);
 #else
 static inline int
-pnfs_report_layoutstat(struct inode *inode)
+pnfs_report_layoutstat(struct inode *inode, gfp_t gfp_flags)
 {
 	return 0;
 }