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Message-ID: <20120614001531.GB22646@thunk.org> Date: Wed, 13 Jun 2012 20:15:31 -0400 From: Ted Ts'o <tytso@....edu> To: Zheng Liu <gnehzuil.liu@...il.com> Cc: linux-ext4@...r.kernel.org, Zheng Liu <wenqing.lz@...bao.com> Subject: Re: [PATCH RESEND] ext4: make sure O_(D)SYNC semantic in ext4_fallocate() Hi Zheng, I finally got around to reviewing this patch and I had one comment > Ext4 must make sure the transaction to be commited to the disk when > user opens a file with O_(D)SYNC flag and do a fallocate(2) call. > > diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c > index 74f23c2..00e32d9 100644 > --- a/fs/ext4/extents.c > +++ b/fs/ext4/extents.c > @@ -4356,6 +4356,8 @@ retry: > ret = PTR_ERR(handle); > break; > } > + if (file->f_flags & O_SYNC) > + ext4_handle_sync(handle); > ret = ext4_map_blocks(handle, inode, &map, flags); > if (ret <= 0) { > #ifdef EXT4FS_DEBUG For a large fallocate(), it can require multiple calls to ext4_map_blocks(), and we should only sync after we've allocated the last segment. We should also not force a sync if there is an error allocating blocks. So it seems to me this patch would be better; what do you think? - Ted commit b790d70be9515dfaba59b0be0aff373e6867826d Author: Zheng Liu <gnehzuil.liu@...il.com> Date: Wed Jun 13 20:15:01 2012 -0400 ext4: honor O_(D)SYNC semantic in ext4_fallocate() Ext4 must make sure the transaction to be commited to the disk when user opens a file with O_(D)SYNC flag and do a fallocate(2) call. This problem had been reported by Christoph Hellwig in this thread: http://www.spinics.net/lists/linux-btrfs/msg13621.html Reported-by: Christoph Hellwig <hch@...radead.org> Signed-off-by: Zheng Liu <wenqing.lz@...bao.com> Signed-off-by: "Theodore Ts'o" <tytso@....edu> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index 91341ec..f1089cb 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -4420,6 +4420,8 @@ retry: ext4_falloc_update_inode(inode, mode, new_size, (map.m_flags & EXT4_MAP_NEW)); ext4_mark_inode_dirty(handle, inode); + if ((file->f_flags & O_SYNC) && ret >= max_blocks) + ext4_handle_sync(handle); ret2 = ext4_journal_stop(handle); if (ret2) break; -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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