> -----Original Message----- > From: Fan Li [mailto:fanofcode...@samsung.com] > Sent: Thursday, December 31, 2015 11:37 AM > To: 'Chao Yu'; 'Jaegeuk Kim' > Cc: linux-f2fs-devel@lists.sourceforge.net > Subject: Re: [f2fs-dev] [PATCH 2/3] f2fs: support finding extents after isize > > > > > -----Original Message----- > > From: Chao Yu [mailto:c...@kernel.org] > > Sent: Wednesday, December 30, 2015 9:28 PM > > To: Fan Li; 'Jaegeuk Kim' > > Cc: linux-f2fs-devel@lists.sourceforge.net > > Subject: Re: [f2fs-dev] [PATCH 2/3] f2fs: support finding extents after > > isize > > > > Hi, > > > > On 12/30/15 5:17 PM, Fan Li wrote: > > > f2fs allows preallocation beyond isize, but f2fs_fiemap only look up > > > extents within isize. Therefore add this support. > > > > > > Note: It's possible that there are holes after isize, for example, > > > fallocate multiple discontinuous extents after isize with > > > FALLOC_FL_KEEP_SIZE set. Since I can tell no differences between EOF > > > and holes from return of get_data_block, I'm afaid this patch can't > > > support such scenarios. > > > > As you mentioned, preallocated block beyond isize can be allocated in f2fs, > > and we are trying > to support mapping extents across > > whole data space of inode, so why we treat theses extents inside i_size and > > outside i_size > separately? IMO, instead using i_size, > we > > should use max blocks as boundary. > > > > Most important, this interface still can't support finding all extents > > after i_size, which > looks buggy for our user. > > Notice that this issue exists before my patch, by adding this patch, at least > now it can support > more scenarios > such as fallocate a range right after isize. I'd say it's an improvement.
Nope, what I'm talking about is *correctness* of our ->fiemap interface, but you're trying to avoid it by saying "support more cases, it's an improvement". That doesn't make any sense to me, since correctness issue still not be fixed. > > use max blocks as boundary would get us the precise result, but it also means > after we reach > the EOF, we still > need to look up every block between the EOF and sb-> s_maxbytes to make sure > the EOF is true, > that's > about 4TB or 10^9 blocks. > And it affects all scenarios where the search range covers the last extent in > the file, not > just extents beyond > isize. I think this price is too high to pay. That's another performance issue. > > I was hoping that I can make f2fs_map_block return an EOF to solve this > problem some time later, > or anyone > have a better idea? At least we can seek valid dnode block like the way llseek use. In addition, for most cases, few of i_nid[5] in f2fs_inode will be NULL, we could skip searching all dnode block in such non-allocated indirect node, instead of searching dnode block f2fs_map_block one by one. Thanks, > > > > > Thanks, > > > > > > > > > > > Signed-off-by: Fan li <fanofcode...@samsung.com> > > > --- > > > fs/f2fs/data.c | 7 +------ > > > 1 file changed, 1 insertion(+), 6 deletions(-) > > > > > > diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c index a9a4d89..f89cf07 > > > 100644 > > > --- a/fs/f2fs/data.c > > > +++ b/fs/f2fs/data.c > > > @@ -798,12 +798,6 @@ int f2fs_fiemap(struct inode *inode, struct > > > fiemap_extent_info *fieinfo, > > > isize = i_size_read(inode); > > > > > > mutex_lock(&inode->i_mutex); > > > - if (start >= isize) > > > - goto out; > > > - > > > - if (start + len > isize) > > > - len = isize - start; > > > - > > > if (logical_to_blk(inode, len) == 0) > > > len = blk_to_logical(inode, 1); > > > > > > @@ -829,6 +823,7 @@ next: > > > * punch holes beyond isize and keep size unchanged. > > > */ > > > flags |= FIEMAP_EXTENT_LAST; > > > + last_blk = start_blk - 1; > > > } > > > > > > if (size) > > > > > > ------------------------------------------------------------------------------ > _______________________________________________ > Linux-f2fs-devel mailing list > Linux-f2fs-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel ------------------------------------------------------------------------------ _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
