xfs: kill XBF_DONTBLOCK

Just about all callers of xfs_buf_read() and xfs_buf_get() use XBF_DONTBLOCK.
This is used to make memory allocation use GFP_NOFS rather than GFP_KERNEL to
avoid recursion through memory reclaim back into the filesystem.

All the blocking get calls in growfs occur inside a transaction, even though
they are no part of the transaction, so all allocation will be GFP_NOFS due to
the task flag PF_TRANS being set. The blocking read calls occur during log
recovery, so they will probably be unaffected by converting to GFP_NOFS
allocations.

Hence make XBF_DONTBLOCK behaviour always occur for buffers and kill the flag.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

1 files changed, 7 insertions, 11 deletions

diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index 8366348aa1f..59e39160d37 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -56,11 +56,7 @@ static struct workqueue_struct *xfslogd_workqueue;
 #endif
 
 #define xb_to_gfp(flags) \
-        ((((flags) & XBF_READ_AHEAD) ? __GFP_NORETRY : \
-          ((flags) & XBF_DONT_BLOCK) ? GFP_NOFS : GFP_KERNEL) | __GFP_NOWARN)
-
-#define xb_to_km(flags) \
-         (((flags) & XBF_DONT_BLOCK) ? KM_NOFS : KM_SLEEP)
+        ((((flags) & XBF_READ_AHEAD) ? __GFP_NORETRY : GFP_NOFS) | __GFP_NOWARN)
 
 
 static inline int
@@ -178,14 +174,14 @@ xfs_buf_alloc(
 {
         struct xfs_buf          *bp;
 
-        bp = kmem_zone_zalloc(xfs_buf_zone, xb_to_km(flags));
+        bp = kmem_zone_zalloc(xfs_buf_zone, KM_NOFS);
         if (unlikely(!bp))
                 return NULL;
 
         /*
          * We don't want certain flags to appear in b_flags.
          */
-        flags &= ~(XBF_MAPPED|XBF_DONT_BLOCK|XBF_READ_AHEAD);
+        flags &= ~(XBF_MAPPED|XBF_READ_AHEAD);
 
         atomic_set(&bp->b_hold, 1);
         atomic_set(&bp->b_lru_ref, 1);
@@ -239,7 +235,7 @@ _xfs_buf_get_pages(
                         bp->b_pages = bp->b_page_array;
                 } else {
                         bp->b_pages = kmem_alloc(sizeof(struct page *) *
-                                        page_count, xb_to_km(flags));
+                                                 page_count, KM_NOFS);
                         if (bp->b_pages == NULL)
                                 return -ENOMEM;
                 }
@@ -316,7 +312,7 @@ xfs_buf_allocate_memory(
          */
         size = BBTOB(bp->b_length);
         if (size < PAGE_SIZE) {
-                bp->b_addr = kmem_alloc(size, xb_to_km(flags));
+                bp->b_addr = kmem_alloc(size, KM_NOFS);
                 if (!bp->b_addr) {
                         /* low memory - use alloc_page loop instead */
                         goto use_alloc_page;
@@ -659,7 +655,7 @@ xfs_buf_readahead(
                 return;
 
         xfs_buf_read(target, blkno, numblks,
-                     XBF_TRYLOCK|XBF_ASYNC|XBF_READ_AHEAD|XBF_DONT_BLOCK);
+                     XBF_TRYLOCK|XBF_ASYNC|XBF_READ_AHEAD);
 }
 
 /*
@@ -750,7 +746,7 @@ xfs_buf_associate_memory(
         bp->b_pages = NULL;
         bp->b_addr = mem;
 
-        rval = _xfs_buf_get_pages(bp, page_count, XBF_DONT_BLOCK);
+        rval = _xfs_buf_get_pages(bp, page_count, 0);
         if (rval)
                 return rval;