| Message ID | 20100816191319.GC5786@mail.oracle.com |
|---|---|
| State | Accepted, archived |
| Headers | show |
On Mon 16-08-10 12:13:19, Joel Becker wrote: > On Mon, Aug 16, 2010 at 09:44:35AM -0500, Eric Sandeen wrote: > > Joel Becker wrote: > > > How about: > > > > > > u64 last_fs_page = last_fs_block >> (PAGE_CACHE_SHIFT - blocksize_bits); > > > > > > ... || > > > (last_fs_page > (pgoff_t)(~0ULL))) { > > > > > > Is that more readable? > > > > To me, yes. Maybe do similar for last_fs_sector. > > last_fs_sector would be shifting up, which could wrap a really > large last_fs_blocks. So I'm going to keep the sector_t check as-is. > How's this: > > >From 8de5cb9164cdc179ba84a07b282a895d0eb794b0 Mon Sep 17 00:00:00 2001 > >From: Joel Becker <joel.becker@oracle.com> > Date: Mon, 16 Aug 2010 12:10:17 -0700 > Subject: [PATCH] libfs: Fix shift bug in generic_check_addressable() > > generic_check_addressable() erroneously shifts pages down by a block > factor when it should be shifting up. To prevent overflow, we shift > blocks down to pages. > > Signed-off-by: Joel Becker <joel.becker@oracle.com> Looks good. Reviewed-by: Jan Kara <jack@suse.cz> Honza > --- > fs/libfs.c | 8 ++++---- > 1 files changed, 4 insertions(+), 4 deletions(-) > > diff --git a/fs/libfs.c b/fs/libfs.c > index 8debe7b..62baa03 100644 > --- a/fs/libfs.c > +++ b/fs/libfs.c > @@ -925,6 +925,8 @@ EXPORT_SYMBOL(generic_file_fsync); > int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks) > { > u64 last_fs_block = num_blocks - 1; > + u64 last_fs_page = > + last_fs_block >> (PAGE_CACHE_SHIFT - blocksize_bits); > > if (unlikely(num_blocks == 0)) > return 0; > @@ -932,10 +934,8 @@ int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks) > if ((blocksize_bits < 9) || (blocksize_bits > PAGE_CACHE_SHIFT)) > return -EINVAL; > > - if ((last_fs_block > > - (sector_t)(~0ULL) >> (blocksize_bits - 9)) || > - (last_fs_block > > - (pgoff_t)(~0ULL) >> (PAGE_CACHE_SHIFT - blocksize_bits))) { > + if ((last_fs_block > (sector_t)(~0ULL) >> (blocksize_bits - 9)) || > + (last_fs_page > (pgoff_t)(~0ULL))) { > return -EFBIG; > } > return 0; > -- > 1.7.1 > > -- > > Life's Little Instruction Book #267 > > "Lie on your back and look at the stars." > > Joel Becker > Consulting Software Developer > Oracle > E-mail: joel.becker@oracle.com > Phone: (650) 506-8127
On Mon, Aug 16, 2010 at 09:21:00PM +0200, Jan Kara wrote: > On Mon 16-08-10 12:13:19, Joel Becker wrote: > > On Mon, Aug 16, 2010 at 09:44:35AM -0500, Eric Sandeen wrote: > > > Joel Becker wrote: > > > > How about: > > > > > > > > u64 last_fs_page = last_fs_block >> (PAGE_CACHE_SHIFT - blocksize_bits); > > > > > > > > ... || > > > > (last_fs_page > (pgoff_t)(~0ULL))) { > > > > > > > > Is that more readable? > > > > > > To me, yes. Maybe do similar for last_fs_sector. > > > > last_fs_sector would be shifting up, which could wrap a really > > large last_fs_blocks. So I'm going to keep the sector_t check as-is. > > How's this: > > > > >From 8de5cb9164cdc179ba84a07b282a895d0eb794b0 Mon Sep 17 00:00:00 2001 > > >From: Joel Becker <joel.becker@oracle.com> > > Date: Mon, 16 Aug 2010 12:10:17 -0700 > > Subject: [PATCH] libfs: Fix shift bug in generic_check_addressable() > > > > generic_check_addressable() erroneously shifts pages down by a block > > factor when it should be shifting up. To prevent overflow, we shift > > blocks down to pages. > > > > Signed-off-by: Joel Becker <joel.becker@oracle.com> > Looks good. > Reviewed-by: Jan Kara <jack@suse.cz> Ok, I'm going to keep this atop my existing branch, and if it all shakes out in linux-next for a few days, send it along. Joel
diff --git a/fs/libfs.c b/fs/libfs.c index 8debe7b..62baa03 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -925,6 +925,8 @@ EXPORT_SYMBOL(generic_file_fsync); int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks) { u64 last_fs_block = num_blocks - 1; + u64 last_fs_page = + last_fs_block >> (PAGE_CACHE_SHIFT - blocksize_bits); if (unlikely(num_blocks == 0)) return 0; @@ -932,10 +934,8 @@ int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks) if ((blocksize_bits < 9) || (blocksize_bits > PAGE_CACHE_SHIFT)) return -EINVAL; - if ((last_fs_block > - (sector_t)(~0ULL) >> (blocksize_bits - 9)) || - (last_fs_block > - (pgoff_t)(~0ULL) >> (PAGE_CACHE_SHIFT - blocksize_bits))) { + if ((last_fs_block > (sector_t)(~0ULL) >> (blocksize_bits - 9)) || + (last_fs_page > (pgoff_t)(~0ULL))) { return -EFBIG; } return 0;