On 09/28/2011 04:11 PM, Yongqiang Yang wrote: > On Wed, Sep 28, 2011 at 4:02 PM, Jeff Liu <jeff.liu@xxxxxxxxxx> wrote: >> On 09/28/2011 03:21 PM, Yongqiang Yang wrote: >> >>> On Wed, Sep 28, 2011 at 2:32 PM, Jeff Liu <jeff.liu@xxxxxxxxxx> wrote: >>>> Hello all, >>>> >>>> This is the V2 for add SEEK_DATA/SEEK_HOLE support to ext4. >>>> In V1, I copied all the codes regarding fetching delayed-extents out to >>>> my seek callback function, it's stupid to duplicate the code blocks. >>>> >>>> Now the idea is, since the delayed-extents is the main concern to search >>>> extents for both fiemap and seek, so IMHO, it's better to consolidate >>>> this procedure into a new function(get_delayed_extent() in my patch), >>>> and call it in fiemap and seek call-back functions if necessary. In >>>> this way, when yongqiang's delayed-extents tree is ready, we only need >>>> to modify the code block at get_delayed_extent() accordingly. >>>> >>>> In addition, yongqiang has pointed out there might be a deadlock, but >>>> per my understood, as the target inode already locked via i_mutex in >>>> ext4_llseek() before, this lock can prevent any modification to the >>>> file, and we call find_get_pages_tag() when trying to fetch the dirty >>>> pages, this function using rcu read lock, it also safe to read. So I >>>> have no idea what's wrong, could anyone please kindly point me out in >>>> this case? I'm definitely a newbie to this list, sorry for my ignorant. >>> Ok. There is no deadlock, fiemap releases i_data_sem before calling >>> get_delayed_extent(). >>> >>> BTW: It seems that there is a bug in fiemap according to code, I am >>> not sure which commit introduced it, delayed extents beyond last >>> allocated block are ignored. >> >> Hmm... could you show me a bit more detailed info with the test scenario >> if convenient? I can help testing, at least 3.1.0-rc2+ is works to me. > Could you test a file with map info like AAAADDDDDHHHHDDDD, > A-allocated block, D-deayed block, H-hole. then filefrag -v and have > a look if extent map info is right. Do you means, open a file, write something, fsync(), then write something, seek to some position and write something again? If so, looks the filefrag -v result is ok by waiting for a few seconds. Thanks, -Jeff > > Thanks, > Yongqiang. >> >> Also, upstream coreutils-cp(1) has been well tested for ext4, it could >> be used for fiemap tests based on the extent_scan module: >> http://git.savannah.gnu.org/cgit/coreutils.git/tree/src/extent-scan.c?h=next&id=b56b53bd70b1f8fa2b5a95d4569bb72a2419b5cd >> >> Thanks, >> -Jeff >> >>> >>> Yongqiang. >>>> >>>> Anyway, I'd like to post the revised for your guys review first. >>>> In have split the modification to two patches this time, since I hope to >>>> make it looks more convenient for the review purpose. >>>> >>>> The 1st patch, remove the delayed-extents fetching procedure to a >>>> function named as get_delayed_extent(), and modify the >>>> ext4_ext_fiemap_cb() accordingly. >>>> >>>> The 2nd path add the ext4_ext_seek_cb() to implement the >>>> SEEK_HOLE/SEEK_DATA stuff based on previous code change. >>>> >>>> Testing: >>>> ======== >>>> In addition to the test cases mentioned in V1, I also done another tests >>>> through sunil's seek test program, please refer to: >>>> http://oss.oracle.com/~smushran/seek_data/seek_test.c >>>> >>>> To ensure the 1st patch does not cause regression issue on fiemap, I >>>> have done some tests via cp(1) with fiemap copy support, the sparse file >>>> used for this test is produced by: >>>> python -c "f=open('./sptest', 'w'); [(f.seek(x) or f.write(str(x))) for >>>> x in range(1, 1000000000, 99999)]; f.close() >>>> >>>> >>>> Any feedback are appreciated! >>>> >>>> >>>> Thanks, >>>> -Jeff >>>> >>> >>> >>> >> >> >> > > > -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
