diff options
| author | Kees Cook <keescook@chromium.org> | 2018-05-29 16:44:59 -0700 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2018-05-30 17:15:43 +0200 |
| commit | 1389053e1bed93b75b0c3cd292f61032334c81b3 (patch) | |
| tree | 71087216205118034caf293b8bf84090bc791bac /fs/btrfs | |
| parent | 090a127afa8f73e9618d4058d6755f7ec7453dd6 (diff) | |
| download | linux-1389053e1bed93b75b0c3cd292f61032334c81b3.tar.gz | |
btrfs: raid56: Remove VLA usage
In the quest to remove all stack VLA usage from the kernel[1], this allocates the working buffers during regular init, instead of using stack space. This refactors the allocation code a bit to make it easier to review. [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com Signed-off-by: Kees Cook <keescook@chromium.org> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs')
| -rw-r--r-- | fs/btrfs/raid56.c | 38 |
1 files changed, 28 insertions, 10 deletions
diff --git a/fs/btrfs/raid56.c b/fs/btrfs/raid56.c index 9abd950e7f78..5e4ad134b9ad 100644 --- a/fs/btrfs/raid56.c +++ b/fs/btrfs/raid56.c @@ -163,6 +163,12 @@ struct btrfs_raid_bio { * bitmap to record which horizontal stripe has data */ unsigned long *dbitmap; + + /* allocated with real_stripes-many pointers for finish_*() calls */ + void **finish_pointers; + + /* allocated with stripe_npages-many bits for finish_*() calls */ + unsigned long *finish_pbitmap; }; static int __raid56_parity_recover(struct btrfs_raid_bio *rbio); @@ -981,9 +987,14 @@ static struct btrfs_raid_bio *alloc_rbio(struct btrfs_fs_info *fs_info, int stripe_npages = DIV_ROUND_UP(stripe_len, PAGE_SIZE); void *p; - rbio = kzalloc(sizeof(*rbio) + num_pages * sizeof(struct page *) * 2 + - DIV_ROUND_UP(stripe_npages, BITS_PER_LONG) * - sizeof(long), GFP_NOFS); + rbio = kzalloc(sizeof(*rbio) + + sizeof(*rbio->stripe_pages) * num_pages + + sizeof(*rbio->bio_pages) * num_pages + + sizeof(*rbio->finish_pointers) * real_stripes + + sizeof(*rbio->dbitmap) * BITS_TO_LONGS(stripe_npages) + + sizeof(*rbio->finish_pbitmap) * + BITS_TO_LONGS(stripe_npages), + GFP_NOFS); if (!rbio) return ERR_PTR(-ENOMEM); @@ -1005,13 +1016,20 @@ static struct btrfs_raid_bio *alloc_rbio(struct btrfs_fs_info *fs_info, atomic_set(&rbio->stripes_pending, 0); /* - * the stripe_pages and bio_pages array point to the extra + * the stripe_pages, bio_pages, etc arrays point to the extra * memory we allocated past the end of the rbio */ p = rbio + 1; - rbio->stripe_pages = p; - rbio->bio_pages = p + sizeof(struct page *) * num_pages; - rbio->dbitmap = p + sizeof(struct page *) * num_pages * 2; +#define CONSUME_ALLOC(ptr, count) do { \ + ptr = p; \ + p = (unsigned char *)p + sizeof(*(ptr)) * (count); \ + } while (0) + CONSUME_ALLOC(rbio->stripe_pages, num_pages); + CONSUME_ALLOC(rbio->bio_pages, num_pages); + CONSUME_ALLOC(rbio->finish_pointers, real_stripes); + CONSUME_ALLOC(rbio->dbitmap, BITS_TO_LONGS(stripe_npages)); + CONSUME_ALLOC(rbio->finish_pbitmap, BITS_TO_LONGS(stripe_npages)); +#undef CONSUME_ALLOC if (bbio->map_type & BTRFS_BLOCK_GROUP_RAID5) nr_data = real_stripes - 1; @@ -1180,7 +1198,7 @@ static void index_rbio_pages(struct btrfs_raid_bio *rbio) static noinline void finish_rmw(struct btrfs_raid_bio *rbio) { struct btrfs_bio *bbio = rbio->bbio; - void *pointers[rbio->real_stripes]; + void **pointers = rbio->finish_pointers; int nr_data = rbio->nr_data; int stripe; int pagenr; @@ -2350,8 +2368,8 @@ static noinline void finish_parity_scrub(struct btrfs_raid_bio *rbio, int need_check) { struct btrfs_bio *bbio = rbio->bbio; - void *pointers[rbio->real_stripes]; - DECLARE_BITMAP(pbitmap, rbio->stripe_npages); + void **pointers = rbio->finish_pointers; + unsigned long *pbitmap = rbio->finish_pbitmap; int nr_data = rbio->nr_data; int stripe; int pagenr; |