Re: [PATCH] fix uncheck memory allocations

[Tsutomu Itoh <t-itoh@jp.fujitsu.com>]

(2011/02/12 20:17), Yoshinori Sano wrote:
> To make Btrfs code more robust, several return value checks where memory
> allocation can fail are introduced.  I use BUG_ON where I don't know how
> to handle the error properly, which increases the number of using the
> notorious BUG_ON, though.
> 
> Signed-off-by: Yoshinori Sano <yoshinori.sano@gmail.com>
> ---
>  fs/btrfs/compression.c |    6 ++++++
>  fs/btrfs/extent-tree.c |    2 ++
>  fs/btrfs/file.c        |    8 ++++++--
>  fs/btrfs/inode.c       |    5 +++++
>  4 files changed, 19 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
> index 4d2110e..f596554 100644
> --- a/fs/btrfs/compression.c
> +++ b/fs/btrfs/compression.c
> @@ -340,6 +340,8 @@ int btrfs_submit_compressed_write(struct inode *inode, u64 start,
>  
>  	WARN_ON(start & ((u64)PAGE_CACHE_SIZE - 1));
>  	cb = kmalloc(compressed_bio_size(root, compressed_len), GFP_NOFS);
> +	if (!cb)
> +		return -ENOMEM;
>  	atomic_set(&cb->pending_bios, 0);
>  	cb->errors = 0;
>  	cb->inode = inode;
> @@ -354,6 +356,10 @@ int btrfs_submit_compressed_write(struct inode *inode, u64 start,
>  	bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
>  
>  	bio = compressed_bio_alloc(bdev, first_byte, GFP_NOFS);
> +	if (!bio) {
> +		kfree(cb);
> +		return -ENOMEM;
> +	}
>  	bio->bi_private = cb;
>  	bio->bi_end_io = end_compressed_bio_write;
>  	atomic_inc(&cb->pending_bios);
> diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
> index 565e22d..aed16f4 100644
> --- a/fs/btrfs/extent-tree.c
> +++ b/fs/btrfs/extent-tree.c
> @@ -6931,6 +6931,8 @@ static noinline int get_new_locations(struct inode *reloc_inode,
>  			struct disk_extent *old = exts;
>  			max *= 2;
>  			exts = kzalloc(sizeof(*exts) * max, GFP_NOFS);
> +			if (!exts)
> +				goto out;
>  			memcpy(exts, old, sizeof(*exts) * nr);
>  			if (old != *extents)
>  				kfree(old);
> diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
> index b0ff34b..4895ad2 100644
> --- a/fs/btrfs/file.c
> +++ b/fs/btrfs/file.c
> @@ -181,10 +181,14 @@ int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
>  		testend = 0;
>  	}
>  	while (1) {
> -		if (!split)
> +		if (!split) {
>  			split = alloc_extent_map(GFP_NOFS);
> -		if (!split2)
> +			BUG_ON(!split || IS_ERR(split));

alloc_extent_map() returns only the address or NULL.
Therefore, I think that check by IS_ERR() is unnecessary.

Regards,
Itoh

> +		}
> +		if (!split2) {
>  			split2 = alloc_extent_map(GFP_NOFS);
> +			BUG_ON(!split2 || IS_ERR(split2));
> +		}
>  
>  		write_lock(&em_tree->lock);
>  		em = lookup_extent_mapping(em_tree, start, len);
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index c9bc0af..40bbe00 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -287,6 +287,7 @@ static noinline int add_async_extent(struct async_cow *cow,
>  	struct async_extent *async_extent;
>  
>  	async_extent = kmalloc(sizeof(*async_extent), GFP_NOFS);
> +	BUG_ON(!async_extent);
>  	async_extent->start = start;
>  	async_extent->ram_size = ram_size;
>  	async_extent->compressed_size = compressed_size;
> @@ -384,6 +385,7 @@ again:
>  	     (BTRFS_I(inode)->force_compress))) {
>  		WARN_ON(pages);
>  		pages = kzalloc(sizeof(struct page *) * nr_pages, GFP_NOFS);
> +		BUG_ON(!pages);
>  
>  		if (BTRFS_I(inode)->force_compress)
>  			compress_type = BTRFS_I(inode)->force_compress;
> @@ -644,6 +646,7 @@ retry:
>  					async_extent->ram_size - 1, 0);
>  
>  		em = alloc_extent_map(GFP_NOFS);
> +		BUG_ON(!em || IS_ERR(em));
>  		em->start = async_extent->start;
>  		em->len = async_extent->ram_size;
>  		em->orig_start = em->start;
> @@ -820,6 +823,7 @@ static noinline int cow_file_range(struct inode *inode,
>  		BUG_ON(ret);
>  
>  		em = alloc_extent_map(GFP_NOFS);
> +		BUG_ON(!em || IS_ERR(em));
>  		em->start = start;
>  		em->orig_start = em->start;
>  		ram_size = ins.offset;
> @@ -1169,6 +1173,7 @@ out_check:
>  			struct extent_map_tree *em_tree;
>  			em_tree = &BTRFS_I(inode)->extent_tree;
>  			em = alloc_extent_map(GFP_NOFS);
> +			BUG_ON(!em || IS_ERR(em));
>  			em->start = cur_offset;
>  			em->orig_start = em->start;
>  			em->len = num_bytes;