xfs: use kvmalloc for xattr buffers

Pankaj Raghav reported that when filesystem block size is larger
than page size, the xattr code can use kmalloc() for high order
allocations. This triggers a useless warning in the allocator as it
is a __GFP_NOFAIL allocation here:

static inline
struct page *rmqueue(struct zone *preferred_zone,
                        struct zone *zone, unsigned int order,
                        gfp_t gfp_flags, unsigned int alloc_flags,
                        int migratetype)
{
        struct page *page;

        /*
         * We most definitely don't want callers attempting to
         * allocate greater than order-1 page units with __GFP_NOFAIL.
         */
>>>>    WARN_ON_ONCE((gfp_flags & __GFP_NOFAIL) && (order > 1));
...

Fix this by changing all these call sites to use kvmalloc(), which
will strip the NOFAIL from the kmalloc attempt and if that fails
will do a __GFP_NOFAIL vmalloc().

This is not an issue that productions systems will see as
filesystems with block size > page size cannot be mounted by the
kernel; Pankaj is developing this functionality right now.

Reported-by: Pankaj Raghav <kernel@pankajraghav.com>
Fixes: f078d4ea8276 ("xfs: convert kmem_alloc() to kmalloc()")
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Link: https://lore.kernel.org/r/20240822135018.1931258-8-kernel@pankajraghav.com
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Pankaj Raghav <p.raghav@samsung.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Daniel Gomez <da.gomez@samsung.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/fs/xfs/libxfs/xfs_attr_leaf.c b/fs/xfs/libxfs/xfs_attr_leaf.c
index b9e98950eb3d81c3cf90e996e34584ce3a82ca6c..09f4cb061a6e0022f73eec32fbb36e76b470cd28 100644 (file)
--- a/fs/xfs/libxfs/xfs_attr_leaf.c
+++ b/fs/xfs/libxfs/xfs_attr_leaf.c
@@ -1138,10 +1138,7 @@ xfs_attr3_leaf_to_shortform(
 
        trace_xfs_attr_leaf_to_sf(args);
 
-       tmpbuffer = kmalloc(args->geo->blksize, GFP_KERNEL | __GFP_NOFAIL);
-       if (!tmpbuffer)
-               return -ENOMEM;
-
+       tmpbuffer = kvmalloc(args->geo->blksize, GFP_KERNEL | __GFP_NOFAIL);
        memcpy(tmpbuffer, bp->b_addr, args->geo->blksize);
 
        leaf = (xfs_attr_leafblock_t *)tmpbuffer;
@@ -1205,7 +1202,7 @@ xfs_attr3_leaf_to_shortform(
        error = 0;
 
 out:
-       kfree(tmpbuffer);
+       kvfree(tmpbuffer);
        return error;
 }
 
@@ -1613,7 +1610,7 @@ xfs_attr3_leaf_compact(
 
        trace_xfs_attr_leaf_compact(args);
 
-       tmpbuffer = kmalloc(args->geo->blksize, GFP_KERNEL | __GFP_NOFAIL);
+       tmpbuffer = kvmalloc(args->geo->blksize, GFP_KERNEL | __GFP_NOFAIL);
        memcpy(tmpbuffer, bp->b_addr, args->geo->blksize);
        memset(bp->b_addr, 0, args->geo->blksize);
        leaf_src = (xfs_attr_leafblock_t *)tmpbuffer;
@@ -1651,7 +1648,7 @@ xfs_attr3_leaf_compact(
         */
        xfs_trans_log_buf(trans, bp, 0, args->geo->blksize - 1);
 
-       kfree(tmpbuffer);
+       kvfree(tmpbuffer);
 }
 
 /*
@@ -2330,7 +2327,7 @@ xfs_attr3_leaf_unbalance(
                struct xfs_attr_leafblock *tmp_leaf;
                struct xfs_attr3_icleaf_hdr tmphdr;
 
-               tmp_leaf = kzalloc(state->args->geo->blksize,
+               tmp_leaf = kvzalloc(state->args->geo->blksize,
                                GFP_KERNEL | __GFP_NOFAIL);
 
                /*
@@ -2371,7 +2368,7 @@ xfs_attr3_leaf_unbalance(
                }
                memcpy(save_leaf, tmp_leaf, state->args->geo->blksize);
                savehdr = tmphdr; /* struct copy */
-               kfree(tmp_leaf);
+               kvfree(tmp_leaf);
        }
 
        xfs_attr3_leaf_hdr_to_disk(state->args->geo, save_leaf, &savehdr);