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. 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 >>> >> >> >> > > > -- Best Wishes Yongqiang Yang -- 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
