* [PATCH] ext4: Create helper function for EXT4_IO_END_UNWRITTEN and i_aiodio_unwritten. @ 2011-08-16 7:06 Tao Ma 2011-08-16 14:04 ` Eric Sandeen 0 siblings, 1 reply; 3+ messages in thread From: Tao Ma @ 2011-08-16 7:06 UTC (permalink / raw) To: linux-ext4; +Cc: Eric Sandeen, Theodore Ts'o From: Tao Ma <boyu.mt@taobao.com> EXT4_IO_END_UNWRITTEN flag set and the increase of i_aiodio_unwritten should be done simultaneously since ext4_end_io_nolock always clear the flag and decrease the counter in the same time. We have found some bugs that the flag is set while leaving i_aiodio_unwritten unchanged. So this patch just tries to creat a helper function to wrap them to avoid any future bug. The idea is inspired by Eric. Cc: Eric Sandeen <sandeen@redhat.com> Cc: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Tao Ma <boyu.mt@taobao.com> --- Ted, This patch is based on the patch with subject "ext4: Resolve the hang of direct i/o read in handling EXT4_IO_END_UNWRITTEN.". I meant it for the next merge window, but if you think it is also ok for 3.1, go ahead. fs/ext4/ext4.h | 11 +++++++++++ fs/ext4/extents.c | 10 ++-------- fs/ext4/inode.c | 5 +---- fs/ext4/page-io.c | 6 ++---- 4 files changed, 16 insertions(+), 16 deletions(-) diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index e717dfd..514f670 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -1247,6 +1247,17 @@ static inline int ext4_valid_inum(struct super_block *sb, unsigned long ino) ino <= le32_to_cpu(EXT4_SB(sb)->s_es->s_inodes_count)); } +static inline int ext4_set_io_unwritten_flag(struct inode *inode, + struct ext4_io_end *io_end) +{ + if (io_end && !(io_end->flag & EXT4_IO_END_UNWRITTEN)) { + io_end->flag |= EXT4_IO_END_UNWRITTEN; + atomic_inc(&EXT4_I(inode)->i_aiodio_unwritten); + return 1; + } + + return 0; +} /* * Inode dynamic state flags */ diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index 57cf568..c0f8655 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -3190,10 +3190,7 @@ ext4_ext_handle_uninitialized_extents(handle_t *handle, struct inode *inode, * that this IO needs to conversion to written when IO is * completed */ - if (io && !(io->flag & EXT4_IO_END_UNWRITTEN)) { - io->flag = EXT4_IO_END_UNWRITTEN; - atomic_inc(&EXT4_I(inode)->i_aiodio_unwritten); - } else + if (!ext4_set_io_unwritten_flag(inode, io)) ext4_set_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN); if (ext4_should_dioread_nolock(inode)) map->m_flags |= EXT4_MAP_UNINIT; @@ -3572,10 +3569,7 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode, * that we need to perform conversion when IO is done. */ if ((flags & EXT4_GET_BLOCKS_PRE_IO)) { - if (io && !(io->flag & EXT4_IO_END_UNWRITTEN)) { - io->flag = EXT4_IO_END_UNWRITTEN; - atomic_inc(&EXT4_I(inode)->i_aiodio_unwritten); - } else + if (!ext4_set_io_unwritten_flag(inode, io)) ext4_set_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN); } diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 40c0b10..128493b 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -2673,10 +2673,7 @@ static void ext4_end_io_buffer_write(struct buffer_head *bh, int uptodate) * but being more careful is always safe for the future change. */ inode = io_end->inode; - if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) { - io_end->flag |= EXT4_IO_END_UNWRITTEN; - atomic_inc(&EXT4_I(inode)->i_aiodio_unwritten); - } + ext4_set_io_unwritten_flag(inode, io_end); /* Add the io_end to per-inode completed io list*/ spin_lock_irqsave(&EXT4_I(inode)->i_completed_io_lock, flags); diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c index 78839af..edd2f7b 100644 --- a/fs/ext4/page-io.c +++ b/fs/ext4/page-io.c @@ -334,10 +334,8 @@ submit_and_retry: if ((io_end->num_io_pages >= MAX_IO_PAGES) && (io_end->pages[io_end->num_io_pages-1] != io_page)) goto submit_and_retry; - if (buffer_uninit(bh) && !(io_end->flag & EXT4_IO_END_UNWRITTEN)) { - io_end->flag |= EXT4_IO_END_UNWRITTEN; - atomic_inc(&EXT4_I(inode)->i_aiodio_unwritten); - } + if (buffer_uninit(bh)) + ext4_set_io_unwritten_flag(inode, io_end); io->io_end->size += bh->b_size; io->io_next_block++; ret = bio_add_page(io->io_bio, bh->b_page, bh->b_size, bh_offset(bh)); -- 1.7.0.4 ^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] ext4: Create helper function for EXT4_IO_END_UNWRITTEN and i_aiodio_unwritten. 2011-08-16 7:06 [PATCH] ext4: Create helper function for EXT4_IO_END_UNWRITTEN and i_aiodio_unwritten Tao Ma @ 2011-08-16 14:04 ` Eric Sandeen 2011-08-17 3:06 ` Tao Ma 0 siblings, 1 reply; 3+ messages in thread From: Eric Sandeen @ 2011-08-16 14:04 UTC (permalink / raw) To: Tao Ma; +Cc: linux-ext4, Theodore Ts'o On 8/16/11 2:06 AM, Tao Ma wrote: > From: Tao Ma <boyu.mt@taobao.com> > > EXT4_IO_END_UNWRITTEN flag set and the increase of i_aiodio_unwritten should > be done simultaneously since ext4_end_io_nolock always clear the flag and > decrease the counter in the same time. > > We have found some bugs that the flag is set while leaving i_aiodio_unwritten > unchanged. So this patch just tries to creat a helper function to wrap them > to avoid any future bug. The idea is inspired by Eric. Although I like it a little less now that I see it in practice, sorry. ;) This: /* * Flag the inode(non aio case) or end_io struct (aio case) * that this IO needs to conversion to written when IO is * completed */ if (!ext4_set_io_unwritten_flag(inode, io)) ext4_set_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN); just reads weirdly to me. It encapsulates all the steps, but it really isn't intuitive to read, I think. "If we (can't? don't?) set the io unwritten flag, set the dio unwritten flag on the inode." I wonder if changing "io" to "endio" would make it a little more obvious. I'm not sure, maybe it's ok. What do others think? I also wonder about this, but I get lost in this code. It was originally: if (io && !(io->flag & EXT4_IO_END_UNWRITTEN)) { io->flag = EXT4_IO_END_UNWRITTEN; atomic_inc(&EXT4_I(inode)->i_aiodio_unwritten); } else ext4_set_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN); That means that if it is AIO ("if (io)"), but the flag is already set (io->flag & EXT4_IO_END_UNWRITTEN), we don't re-set the flag or increase the count, which is fine - but is it then correct to set the state on the inode? thanks, -Eric > Cc: Eric Sandeen <sandeen@redhat.com> > Cc: "Theodore Ts'o" <tytso@mit.edu> > Signed-off-by: Tao Ma <boyu.mt@taobao.com> > --- > Ted, > This patch is based on the patch with subject "ext4: Resolve the hang > of direct i/o read in handling EXT4_IO_END_UNWRITTEN.". I meant it for the next > merge window, but if you think it is also ok for 3.1, go ahead. > > fs/ext4/ext4.h | 11 +++++++++++ > fs/ext4/extents.c | 10 ++-------- > fs/ext4/inode.c | 5 +---- > fs/ext4/page-io.c | 6 ++---- > 4 files changed, 16 insertions(+), 16 deletions(-) > > diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h > index e717dfd..514f670 100644 > --- a/fs/ext4/ext4.h > +++ b/fs/ext4/ext4.h > @@ -1247,6 +1247,17 @@ static inline int ext4_valid_inum(struct super_block *sb, unsigned long ino) > ino <= le32_to_cpu(EXT4_SB(sb)->s_es->s_inodes_count)); > } > > +static inline int ext4_set_io_unwritten_flag(struct inode *inode, > + struct ext4_io_end *io_end) > +{ > + if (io_end && !(io_end->flag & EXT4_IO_END_UNWRITTEN)) { > + io_end->flag |= EXT4_IO_END_UNWRITTEN; > + atomic_inc(&EXT4_I(inode)->i_aiodio_unwritten); > + return 1; > + } > + > + return 0; > +} > /* > * Inode dynamic state flags > */ > diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c > index 57cf568..c0f8655 100644 > --- a/fs/ext4/extents.c > +++ b/fs/ext4/extents.c > @@ -3190,10 +3190,7 @@ ext4_ext_handle_uninitialized_extents(handle_t *handle, struct inode *inode, > * that this IO needs to conversion to written when IO is > * completed > */ > - if (io && !(io->flag & EXT4_IO_END_UNWRITTEN)) { > - io->flag = EXT4_IO_END_UNWRITTEN; > - atomic_inc(&EXT4_I(inode)->i_aiodio_unwritten); > - } else > + if (!ext4_set_io_unwritten_flag(inode, io)) > ext4_set_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN); > if (ext4_should_dioread_nolock(inode)) > map->m_flags |= EXT4_MAP_UNINIT; > @@ -3572,10 +3569,7 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode, > * that we need to perform conversion when IO is done. > */ > if ((flags & EXT4_GET_BLOCKS_PRE_IO)) { > - if (io && !(io->flag & EXT4_IO_END_UNWRITTEN)) { > - io->flag = EXT4_IO_END_UNWRITTEN; > - atomic_inc(&EXT4_I(inode)->i_aiodio_unwritten); > - } else > + if (!ext4_set_io_unwritten_flag(inode, io)) > ext4_set_inode_state(inode, > EXT4_STATE_DIO_UNWRITTEN); > } > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c > index 40c0b10..128493b 100644 > --- a/fs/ext4/inode.c > +++ b/fs/ext4/inode.c > @@ -2673,10 +2673,7 @@ static void ext4_end_io_buffer_write(struct buffer_head *bh, int uptodate) > * but being more careful is always safe for the future change. > */ > inode = io_end->inode; > - if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) { > - io_end->flag |= EXT4_IO_END_UNWRITTEN; > - atomic_inc(&EXT4_I(inode)->i_aiodio_unwritten); > - } > + ext4_set_io_unwritten_flag(inode, io_end); > > /* Add the io_end to per-inode completed io list*/ > spin_lock_irqsave(&EXT4_I(inode)->i_completed_io_lock, flags); > diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c > index 78839af..edd2f7b 100644 > --- a/fs/ext4/page-io.c > +++ b/fs/ext4/page-io.c > @@ -334,10 +334,8 @@ submit_and_retry: > if ((io_end->num_io_pages >= MAX_IO_PAGES) && > (io_end->pages[io_end->num_io_pages-1] != io_page)) > goto submit_and_retry; > - if (buffer_uninit(bh) && !(io_end->flag & EXT4_IO_END_UNWRITTEN)) { > - io_end->flag |= EXT4_IO_END_UNWRITTEN; > - atomic_inc(&EXT4_I(inode)->i_aiodio_unwritten); > - } > + if (buffer_uninit(bh)) > + ext4_set_io_unwritten_flag(inode, io_end); > io->io_end->size += bh->b_size; > io->io_next_block++; > ret = bio_add_page(io->io_bio, bh->b_page, bh->b_size, bh_offset(bh)); ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] ext4: Create helper function for EXT4_IO_END_UNWRITTEN and i_aiodio_unwritten. 2011-08-16 14:04 ` Eric Sandeen @ 2011-08-17 3:06 ` Tao Ma 0 siblings, 0 replies; 3+ messages in thread From: Tao Ma @ 2011-08-17 3:06 UTC (permalink / raw) To: Eric Sandeen; +Cc: linux-ext4, Theodore Ts'o On 08/16/2011 10:04 PM, Eric Sandeen wrote: > On 8/16/11 2:06 AM, Tao Ma wrote: >> From: Tao Ma <boyu.mt@taobao.com> >> >> EXT4_IO_END_UNWRITTEN flag set and the increase of i_aiodio_unwritten should >> be done simultaneously since ext4_end_io_nolock always clear the flag and >> decrease the counter in the same time. >> >> We have found some bugs that the flag is set while leaving i_aiodio_unwritten >> unchanged. So this patch just tries to creat a helper function to wrap them >> to avoid any future bug. The idea is inspired by Eric. > > Although I like it a little less now that I see it in practice, sorry. ;) > > This: > /* > * Flag the inode(non aio case) or end_io struct (aio case) > * that this IO needs to conversion to written when IO is > * completed > */ > if (!ext4_set_io_unwritten_flag(inode, io)) > ext4_set_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN); > > just reads weirdly to me. yeah, this also looks a little bit strange. Another possible way is that we just wrap the set of the flag and the inc of aiodio_unwritten while leave the check there. It should look more natural and good for the reader. > > It encapsulates all the steps, but it really isn't intuitive to read, I think. > > "If we (can't? don't?) set the io unwritten flag, set the dio unwritten flag > on the inode." > > I wonder if changing "io" to "endio" would make it a little more obvious. > > I'm not sure, maybe it's ok. What do others think? > > I also wonder about this, but I get lost in this code. It was originally: > > if (io && !(io->flag & EXT4_IO_END_UNWRITTEN)) { > io->flag = EXT4_IO_END_UNWRITTEN; > atomic_inc(&EXT4_I(inode)->i_aiodio_unwritten); > } else > ext4_set_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN); > > That means that if it is AIO ("if (io)"), but the flag is already set > (io->flag & EXT4_IO_END_UNWRITTEN), we don't re-set the flag or increase > the count, which is fine - but is it then correct to set the state on the > inode? I will check it later. Thanks Tao > > thanks, > -Eric > >> Cc: Eric Sandeen <sandeen@redhat.com> >> Cc: "Theodore Ts'o" <tytso@mit.edu> >> Signed-off-by: Tao Ma <boyu.mt@taobao.com> >> --- >> Ted, >> This patch is based on the patch with subject "ext4: Resolve the hang >> of direct i/o read in handling EXT4_IO_END_UNWRITTEN.". I meant it for the next >> merge window, but if you think it is also ok for 3.1, go ahead. >> >> fs/ext4/ext4.h | 11 +++++++++++ >> fs/ext4/extents.c | 10 ++-------- >> fs/ext4/inode.c | 5 +---- >> fs/ext4/page-io.c | 6 ++---- >> 4 files changed, 16 insertions(+), 16 deletions(-) >> >> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h >> index e717dfd..514f670 100644 >> --- a/fs/ext4/ext4.h >> +++ b/fs/ext4/ext4.h >> @@ -1247,6 +1247,17 @@ static inline int ext4_valid_inum(struct super_block *sb, unsigned long ino) >> ino <= le32_to_cpu(EXT4_SB(sb)->s_es->s_inodes_count)); >> } >> >> +static inline int ext4_set_io_unwritten_flag(struct inode *inode, >> + struct ext4_io_end *io_end) >> +{ >> + if (io_end && !(io_end->flag & EXT4_IO_END_UNWRITTEN)) { >> + io_end->flag |= EXT4_IO_END_UNWRITTEN; >> + atomic_inc(&EXT4_I(inode)->i_aiodio_unwritten); >> + return 1; >> + } >> + >> + return 0; >> +} >> /* >> * Inode dynamic state flags >> */ >> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c >> index 57cf568..c0f8655 100644 >> --- a/fs/ext4/extents.c >> +++ b/fs/ext4/extents.c >> @@ -3190,10 +3190,7 @@ ext4_ext_handle_uninitialized_extents(handle_t *handle, struct inode *inode, >> * that this IO needs to conversion to written when IO is >> * completed >> */ >> - if (io && !(io->flag & EXT4_IO_END_UNWRITTEN)) { >> - io->flag = EXT4_IO_END_UNWRITTEN; >> - atomic_inc(&EXT4_I(inode)->i_aiodio_unwritten); >> - } else >> + if (!ext4_set_io_unwritten_flag(inode, io)) >> ext4_set_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN); >> if (ext4_should_dioread_nolock(inode)) >> map->m_flags |= EXT4_MAP_UNINIT; >> @@ -3572,10 +3569,7 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode, >> * that we need to perform conversion when IO is done. >> */ >> if ((flags & EXT4_GET_BLOCKS_PRE_IO)) { >> - if (io && !(io->flag & EXT4_IO_END_UNWRITTEN)) { >> - io->flag = EXT4_IO_END_UNWRITTEN; >> - atomic_inc(&EXT4_I(inode)->i_aiodio_unwritten); >> - } else >> + if (!ext4_set_io_unwritten_flag(inode, io)) >> ext4_set_inode_state(inode, >> EXT4_STATE_DIO_UNWRITTEN); >> } >> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c >> index 40c0b10..128493b 100644 >> --- a/fs/ext4/inode.c >> +++ b/fs/ext4/inode.c >> @@ -2673,10 +2673,7 @@ static void ext4_end_io_buffer_write(struct buffer_head *bh, int uptodate) >> * but being more careful is always safe for the future change. >> */ >> inode = io_end->inode; >> - if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) { >> - io_end->flag |= EXT4_IO_END_UNWRITTEN; >> - atomic_inc(&EXT4_I(inode)->i_aiodio_unwritten); >> - } >> + ext4_set_io_unwritten_flag(inode, io_end); >> >> /* Add the io_end to per-inode completed io list*/ >> spin_lock_irqsave(&EXT4_I(inode)->i_completed_io_lock, flags); >> diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c >> index 78839af..edd2f7b 100644 >> --- a/fs/ext4/page-io.c >> +++ b/fs/ext4/page-io.c >> @@ -334,10 +334,8 @@ submit_and_retry: >> if ((io_end->num_io_pages >= MAX_IO_PAGES) && >> (io_end->pages[io_end->num_io_pages-1] != io_page)) >> goto submit_and_retry; >> - if (buffer_uninit(bh) && !(io_end->flag & EXT4_IO_END_UNWRITTEN)) { >> - io_end->flag |= EXT4_IO_END_UNWRITTEN; >> - atomic_inc(&EXT4_I(inode)->i_aiodio_unwritten); >> - } >> + if (buffer_uninit(bh)) >> + ext4_set_io_unwritten_flag(inode, io_end); >> io->io_end->size += bh->b_size; >> io->io_next_block++; >> ret = bio_add_page(io->io_bio, bh->b_page, bh->b_size, bh_offset(bh)); > ^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2011-08-17 3:06 UTC | newest] Thread overview: 3+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2011-08-16 7:06 [PATCH] ext4: Create helper function for EXT4_IO_END_UNWRITTEN and i_aiodio_unwritten Tao Ma 2011-08-16 14:04 ` Eric Sandeen 2011-08-17 3:06 ` Tao Ma
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