On 4/27/12 5:47 PM, Bernd Schubert wrote:
> On 04/27/2012 06:21 PM, Eric Sandeen wrote:
...
>> +generic_file_llseek_size_eof(struct file *file, loff_t offset, int origin,
>> + loff_t maxsize, loff_t eof)
>> {
>> struct inode *inode = file->f_mapping->host;
>>
>> switch (origin) {
>> case SEEK_END:
>> - offset += i_size_read(inode);
>> + offset += eof;
>> break;
>
> Here is the only glitch I can see. As Andreas already said before, it
> might overflow here. Do we need do care about that? As you already said,
> SEEK_END is unlikely to be ever called for directories. But then we also
> cannot keep user space from doing weird calls...
It can happen already today, for a sufficiently large file offset.
# ls -l reallybigfile
-rw-r--r--. 1 root root 9223372036854775807 Apr 27 18:02 reallybigfile
(that's 2^63 - 1)
so overflow protection may be warranted in here, but I think it's a separate problem.
...
>> diff --git a/include/linux/fs.h b/include/linux/fs.h
>> index 8de6755..a6ae7a4 100644
>> --- a/include/linux/fs.h
>> +++ b/include/linux/fs.h
>> @@ -2402,6 +2402,8 @@ extern loff_t no_llseek(struct file *file, loff_t offset, int origin);
>> extern loff_t generic_file_llseek(struct file *file, loff_t offset, int origin);
>> extern loff_t generic_file_llseek_size(struct file *file, loff_t offset,
>> int origin, loff_t maxsize);
>> +extern loff_t generic_file_llseek_size_eof(struct file *file, loff_t offset,
>> + int origin, loff_t maxsize, loff_t eof);
>> extern int generic_file_open(struct inode * inode, struct file * filp);
>> extern int nonseekable_open(struct inode * inode, struct file * filp);
>
> Another question, wouldn't it be better to entirely move
> generic_file_llseek_size() and generic_file_llseek() into fs.h to make
> sure it gets inlined?
Hm, perhaps. It wasn't done for generic_file_llseek_size() so I just followed
that example, for now.
-Eric
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