Re: [PATCH] squashfs: avoid bio_alloc() failure with 1Mbyte blocks
On Fri, 14 Aug 2020 21:30:33 -0700 Guenter Roeck wrote: > On Fri, Aug 14, 2020 at 8:57 PM Phillip Lougher > wrote: > > > > This is a regression introduced by the "migrate from ll_rw_block usage > > to BIO" patch. > > > > Bio_alloc() is limited to 256 pages (1 Mbyte). This can cause a > > failure when reading 1 Mbyte block filesystems. The problem is > > a datablock can be fully (or almost uncompressed), requiring 256 > > pages, but, because blocks are not aligned to page boundaries, it > > may require 257 pages to read. > > > > Bio_kmalloc() can handle 1024 pages, and so use this for the > > edge condition. > > > > Reported-by: Nicolas Prochazka > > Reported-by: Tomoatsu Shimada > > Signed-off-by: Phillip Lougher > > Fixes: 93e72b3c612a ("squashfs: migrate from ll_rw_block usage to BIO") > Reviewed-by: Guenter Roeck Thanks. I added cc:stable also.
[PATCH] squashfs: avoid bio_alloc() failure with 1Mbyte blocks
This is a regression introduced by the "migrate from ll_rw_block usage to BIO" patch. Bio_alloc() is limited to 256 pages (1 Mbyte). This can cause a failure when reading 1 Mbyte block filesystems. The problem is a datablock can be fully (or almost uncompressed), requiring 256 pages, but, because blocks are not aligned to page boundaries, it may require 257 pages to read. Bio_kmalloc() can handle 1024 pages, and so use this for the edge condition. Reported-by: Nicolas Prochazka Reported-by: Tomoatsu Shimada Signed-off-by: Phillip Lougher --- fs/squashfs/block.c | 6 +- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/fs/squashfs/block.c b/fs/squashfs/block.c index 76bb1c846845..8a19773b5a0b 100644 --- a/fs/squashfs/block.c +++ b/fs/squashfs/block.c @@ -87,7 +87,11 @@ static int squashfs_bio_read(struct super_block *sb, u64 index, int length, int error, i; struct bio *bio; - bio = bio_alloc(GFP_NOIO, page_count); + if (page_count <= BIO_MAX_PAGES) + bio = bio_alloc(GFP_NOIO, page_count); + else + bio = bio_kmalloc(GFP_NOIO, page_count); + if (!bio) return -ENOMEM; -- 2.20.1
Re: [PATCH] squashfs: avoid bio_alloc() failure with 1Mbyte blocks
On Fri, Aug 14, 2020 at 8:57 PM Phillip Lougher wrote: > > This is a regression introduced by the "migrate from ll_rw_block usage > to BIO" patch. > > Bio_alloc() is limited to 256 pages (1 Mbyte). This can cause a > failure when reading 1 Mbyte block filesystems. The problem is > a datablock can be fully (or almost uncompressed), requiring 256 > pages, but, because blocks are not aligned to page boundaries, it > may require 257 pages to read. > > Bio_kmalloc() can handle 1024 pages, and so use this for the > edge condition. > > Reported-by: Nicolas Prochazka > Reported-by: Tomoatsu Shimada > Signed-off-by: Phillip Lougher Fixes: 93e72b3c612a ("squashfs: migrate from ll_rw_block usage to BIO") Reviewed-by: Guenter Roeck > --- > fs/squashfs/block.c | 6 +- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/fs/squashfs/block.c b/fs/squashfs/block.c > index 76bb1c846845..8a19773b5a0b 100644 > --- a/fs/squashfs/block.c > +++ b/fs/squashfs/block.c > @@ -87,7 +87,11 @@ static int squashfs_bio_read(struct super_block *sb, u64 > index, int length, > int error, i; > struct bio *bio; > > - bio = bio_alloc(GFP_NOIO, page_count); > + if (page_count <= BIO_MAX_PAGES) > + bio = bio_alloc(GFP_NOIO, page_count); > + else > + bio = bio_kmalloc(GFP_NOIO, page_count); > + > if (!bio) > return -ENOMEM; > > -- > 2.20.1 >