[PATCH v11 07/10] xfs: use kvmalloc for xattr buffers

Pankaj Raghav (Samsung)
2024-07-26T12:00:41Z

From: Dave Chinner <dchinner@redhat.com>

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>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Pankaj Raghav <p.raghav@samsung.com>
---
fs/xfs/libxfs/xfs_attr_leaf.c | 15 ++++++---------
1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_attr_leaf.c b/fs/xfs/libxfs/xfs_attr_leaf.c
index b9e98950eb3d8..09f4cb061a6e0 100644
--- 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);
--
2.44.1