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Message-Id: <0C1C222E-9299-4C92-9F16-3D0912E3B50A@dilger.ca>
Date: Thu, 12 Aug 2010 17:07:36 -0600
From: Andreas Dilger <adilger@...ger.ca>
To: Joel Becker <Joel.Becker@...cle.com>
Cc: "Ted Ts'o" <tytso@....edu>, Jan Kara <jack@...e.cz>,
ocfs2-devel@....oracle.com, linux-fsdevel@...r.kernel.org,
linux-ext4@...r.kernel.org,
"linux-kernel@...r.kernel.org Patrick J. LoPresti"
<lopresti@...il.com>
Subject: Re: [Ocfs2-devel] [PATCH 1/3] ext3/ext4: Factor out disk addressability check
You can add my:
Acked-by: Andreas Dilger <adilger@...ger.ca>
On 2010-08-12, at 16:29, Joel Becker wrote:
> On Thu, Aug 12, 2010 at 03:32:27PM -0600, Andreas Dilger wrote:
>>> If I change the BUG_ON()s to -EINVAL, does that work? Or do you
>>> have some way you'd like to allow non-pagecache filesystems to use this
>>> as well?
>>
>> That's probably fine for now. If anyone complains, we can always change it later, since they can't possibly depend on this function yet...
>
> How's this:
>
>> From f988b04c58039ae9a65fea537656088ea56a8072 Mon Sep 17 00:00:00 2001
>> From: Patrick J. LoPresti <lopresti@...il.com>
> Date: Thu, 22 Jul 2010 15:03:41 -0700
> Subject: [PATCH] ext3/ext4: Factor out disk addressability check
>
> As part of adding support for OCFS2 to mount huge volumes, we need to
> check that the sector_t and page cache of the system are capable of
> addressing the entire volume.
>
> An identical check already appears in ext3 and ext4. This patch moves
> the addressability check into its own function in fs/libfs.c and
> modifies ext3 and ext4 to invoke it.
>
> [Edited to -EINVAL instead of BUG_ON() for bad blocksize_bits -- Joel]
>
> Signed-off-by: Patrick LoPresti <lopresti@...il.com>
> Cc: linux-ext4@...r.kernel.org
> Signed-off-by: Joel Becker <joel.becker@...cle.com>
> ---
> fs/ext3/super.c | 4 ++--
> fs/ext4/super.c | 8 +++-----
> fs/libfs.c | 29 +++++++++++++++++++++++++++++
> include/linux/fs.h | 2 ++
> 4 files changed, 36 insertions(+), 7 deletions(-)
>
> diff --git a/fs/ext3/super.c b/fs/ext3/super.c
> index 6c953bb..d0643db 100644
> --- a/fs/ext3/super.c
> +++ b/fs/ext3/super.c
> @@ -1862,8 +1862,8 @@ static int ext3_fill_super (struct super_block *sb, void *data, int silent)
> goto failed_mount;
> }
>
> - if (le32_to_cpu(es->s_blocks_count) >
> - (sector_t)(~0ULL) >> (sb->s_blocksize_bits - 9)) {
> + if (generic_check_addressable(sb->s_blocksize_bits,
> + le32_to_cpu(es->s_blocks_count))) {
> ext3_msg(sb, KERN_ERR,
> "error: filesystem is too large to mount safely");
> if (sizeof(sector_t) < 8)
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index e72d323..e03a7d2 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -2706,15 +2706,13 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
> * Test whether we have more sectors than will fit in sector_t,
> * and whether the max offset is addressable by the page cache.
> */
> - if ((ext4_blocks_count(es) >
> - (sector_t)(~0ULL) >> (sb->s_blocksize_bits - 9)) ||
> - (ext4_blocks_count(es) >
> - (pgoff_t)(~0ULL) >> (PAGE_CACHE_SHIFT - sb->s_blocksize_bits))) {
> + ret = generic_check_addressable(sb->s_blocksize_bits,
> + ext4_blocks_count(es));
> + if (ret) {
> ext4_msg(sb, KERN_ERR, "filesystem"
> " too large to mount safely on this system");
> if (sizeof(sector_t) < 8)
> ext4_msg(sb, KERN_WARNING, "CONFIG_LBDAF not enabled");
> - ret = -EFBIG;
> goto failed_mount;
> }
>
> diff --git a/fs/libfs.c b/fs/libfs.c
> index dcaf972..f099566 100644
> --- a/fs/libfs.c
> +++ b/fs/libfs.c
> @@ -955,6 +955,35 @@ int generic_file_fsync(struct file *file, int datasync)
> }
> EXPORT_SYMBOL(generic_file_fsync);
>
> +/**
> + * generic_check_addressable - Check addressability of file system
> + * @blocksize_bits: log of file system block size
> + * @num_blocks: number of blocks in file system
> + *
> + * Determine whether a file system with @num_blocks blocks (and a
> + * block size of 2**@...cksize_bits) is addressable by the sector_t
> + * and page cache of the system. Return 0 if so and -EFBIG otherwise.
> + */
> +int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks)
> +{
> + u64 last_fs_block = num_blocks - 1;
> +
> + if (unlikely(num_blocks == 0))
> + return 0;
> +
> + 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))) {
> + return -EFBIG;
> + }
> + return 0;
> +}
> +EXPORT_SYMBOL(generic_check_addressable);
> +
> /*
> * No-op implementation of ->fsync for in-memory filesystems.
> */
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index e5106e4..7644248 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -2414,6 +2414,8 @@ extern ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos,
>
> extern int generic_file_fsync(struct file *, int);
>
> +extern int generic_check_addressable(unsigned, u64);
> +
> #ifdef CONFIG_MIGRATION
> extern int buffer_migrate_page(struct address_space *,
> struct page *, struct page *);
> --
> 1.7.1
>
>
> --
>
> "Friends may come and go, but enemies accumulate."
> - Thomas Jones
>
> Joel Becker
> Consulting Software Developer
> Oracle
> E-mail: joel.becker@...cle.com
> Phone: (650) 506-8127
> --
> To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
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> More majordomo info at http://vger.kernel.org/majordomo-info.html
Cheers, Andreas
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