From: Al Viro <viro@zeniv.linux.org.uk>
To: Yangtao Li <frank.li@vivo.com>
Cc: xiang@kernel.org, chao@kernel.org, huyue2@coolpad.com,
jefflexu@linux.alibaba.com, tytso@mit.edu,
adilger.kernel@dilger.ca, rpeterso@redhat.com,
agruenba@redhat.com, mark@fasheh.com, jlbec@evilplan.org,
joseph.qi@linux.alibaba.com, brauner@kernel.org,
linux-erofs@lists.ozlabs.org, linux-kernel@vger.kernel.org,
linux-ext4@vger.kernel.org, cluster-devel@redhat.com,
ocfs2-devel@oss.oracle.com, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH v3 4/6] ext4: convert to use i_blockmask()
Date: Fri, 10 Mar 2023 03:32:13 +0000 [thread overview]
Message-ID: <20230310033213.GG3390869@ZenIV> (raw)
In-Reply-To: <20230310031940.GE3390869@ZenIV>
On Fri, Mar 10, 2023 at 03:19:40AM +0000, Al Viro wrote:
> On Thu, Mar 09, 2023 at 11:21:25PM +0800, Yangtao Li wrote:
> > Use i_blockmask() to simplify code.
> >
> > Signed-off-by: Yangtao Li <frank.li@vivo.com>
> > ---
> > v3:
> > -none
> > v2:
> > -convert to i_blockmask()
> > fs/ext4/inode.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> > index d251d705c276..eec36520e5e9 100644
> > --- a/fs/ext4/inode.c
> > +++ b/fs/ext4/inode.c
> > @@ -2218,7 +2218,7 @@ static int mpage_process_page_bufs(struct mpage_da_data *mpd,
> > {
> > struct inode *inode = mpd->inode;
> > int err;
> > - ext4_lblk_t blocks = (i_size_read(inode) + i_blocksize(inode) - 1)
> > + ext4_lblk_t blocks = (i_size_read(inode) + i_blockmask(inode))
> > >> inode->i_blkbits;
>
> Umm... That actually asks for DIV_ROUND_UP(i_size_read_inode(), i_blocksize(inode)) -
> compiler should bloody well be able to figure out that division by (1 << n) is
> shift down by n and it's easier to follow that way...
BTW, here the fact that you are adding the mask is misleading - it's true,
but we are not using it as a mask - it's straight arithmetics.
One can do an equivalent code where it would've been used as a mask, but that
would be harder to read -
(((i_size_read(inode) - 1) | i_blockmask(inode)) + 1) >> inode->i_blkbits
and I doubt anyone wants that kind of puzzles to stumble upon.
WARNING: multiple messages have this Message-ID (diff)
From: Al Viro via Ocfs2-devel <ocfs2-devel@oss.oracle.com>
To: Yangtao Li <frank.li@vivo.com>
Cc: brauner@kernel.org, tytso@mit.edu, agruenba@redhat.com,
chao@kernel.org, linux-kernel@vger.kernel.org,
cluster-devel@redhat.com, rpeterso@redhat.com,
huyue2@coolpad.com, adilger.kernel@dilger.ca,
jefflexu@linux.alibaba.com, linux-fsdevel@vger.kernel.org,
xiang@kernel.org, linux-ext4@vger.kernel.org,
linux-erofs@lists.ozlabs.org, ocfs2-devel@oss.oracle.com
Subject: Re: [Ocfs2-devel] [PATCH v3 4/6] ext4: convert to use i_blockmask()
Date: Fri, 10 Mar 2023 03:32:13 +0000 [thread overview]
Message-ID: <20230310033213.GG3390869@ZenIV> (raw)
In-Reply-To: <20230310031940.GE3390869@ZenIV>
On Fri, Mar 10, 2023 at 03:19:40AM +0000, Al Viro wrote:
> On Thu, Mar 09, 2023 at 11:21:25PM +0800, Yangtao Li wrote:
> > Use i_blockmask() to simplify code.
> >
> > Signed-off-by: Yangtao Li <frank.li@vivo.com>
> > ---
> > v3:
> > -none
> > v2:
> > -convert to i_blockmask()
> > fs/ext4/inode.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> > index d251d705c276..eec36520e5e9 100644
> > --- a/fs/ext4/inode.c
> > +++ b/fs/ext4/inode.c
> > @@ -2218,7 +2218,7 @@ static int mpage_process_page_bufs(struct mpage_da_data *mpd,
> > {
> > struct inode *inode = mpd->inode;
> > int err;
> > - ext4_lblk_t blocks = (i_size_read(inode) + i_blocksize(inode) - 1)
> > + ext4_lblk_t blocks = (i_size_read(inode) + i_blockmask(inode))
> > >> inode->i_blkbits;
>
> Umm... That actually asks for DIV_ROUND_UP(i_size_read_inode(), i_blocksize(inode)) -
> compiler should bloody well be able to figure out that division by (1 << n) is
> shift down by n and it's easier to follow that way...
BTW, here the fact that you are adding the mask is misleading - it's true,
but we are not using it as a mask - it's straight arithmetics.
One can do an equivalent code where it would've been used as a mask, but that
would be harder to read -
(((i_size_read(inode) - 1) | i_blockmask(inode)) + 1) >> inode->i_blkbits
and I doubt anyone wants that kind of puzzles to stumble upon.
_______________________________________________
Ocfs2-devel mailing list
Ocfs2-devel@oss.oracle.com
https://oss.oracle.com/mailman/listinfo/ocfs2-devel
WARNING: multiple messages have this Message-ID (diff)
From: Al Viro <viro@zeniv.linux.org.uk>
To: Yangtao Li <frank.li@vivo.com>
Cc: brauner@kernel.org, tytso@mit.edu, agruenba@redhat.com,
joseph.qi@linux.alibaba.com, mark@fasheh.com,
linux-kernel@vger.kernel.org, cluster-devel@redhat.com,
rpeterso@redhat.com, huyue2@coolpad.com,
adilger.kernel@dilger.ca, jlbec@evilplan.org,
linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org,
linux-erofs@lists.ozlabs.org, ocfs2-devel@oss.oracle.com
Subject: Re: [PATCH v3 4/6] ext4: convert to use i_blockmask()
Date: Fri, 10 Mar 2023 03:32:13 +0000 [thread overview]
Message-ID: <20230310033213.GG3390869@ZenIV> (raw)
In-Reply-To: <20230310031940.GE3390869@ZenIV>
On Fri, Mar 10, 2023 at 03:19:40AM +0000, Al Viro wrote:
> On Thu, Mar 09, 2023 at 11:21:25PM +0800, Yangtao Li wrote:
> > Use i_blockmask() to simplify code.
> >
> > Signed-off-by: Yangtao Li <frank.li@vivo.com>
> > ---
> > v3:
> > -none
> > v2:
> > -convert to i_blockmask()
> > fs/ext4/inode.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> > index d251d705c276..eec36520e5e9 100644
> > --- a/fs/ext4/inode.c
> > +++ b/fs/ext4/inode.c
> > @@ -2218,7 +2218,7 @@ static int mpage_process_page_bufs(struct mpage_da_data *mpd,
> > {
> > struct inode *inode = mpd->inode;
> > int err;
> > - ext4_lblk_t blocks = (i_size_read(inode) + i_blocksize(inode) - 1)
> > + ext4_lblk_t blocks = (i_size_read(inode) + i_blockmask(inode))
> > >> inode->i_blkbits;
>
> Umm... That actually asks for DIV_ROUND_UP(i_size_read_inode(), i_blocksize(inode)) -
> compiler should bloody well be able to figure out that division by (1 << n) is
> shift down by n and it's easier to follow that way...
BTW, here the fact that you are adding the mask is misleading - it's true,
but we are not using it as a mask - it's straight arithmetics.
One can do an equivalent code where it would've been used as a mask, but that
would be harder to read -
(((i_size_read(inode) - 1) | i_blockmask(inode)) + 1) >> inode->i_blkbits
and I doubt anyone wants that kind of puzzles to stumble upon.
WARNING: multiple messages have this Message-ID (diff)
From: Al Viro <viro@zeniv.linux.org.uk>
To: cluster-devel.redhat.com
Subject: [Cluster-devel] [PATCH v3 4/6] ext4: convert to use i_blockmask()
Date: Fri, 10 Mar 2023 03:32:13 +0000 [thread overview]
Message-ID: <20230310033213.GG3390869@ZenIV> (raw)
In-Reply-To: <20230310031940.GE3390869@ZenIV>
On Fri, Mar 10, 2023 at 03:19:40AM +0000, Al Viro wrote:
> On Thu, Mar 09, 2023 at 11:21:25PM +0800, Yangtao Li wrote:
> > Use i_blockmask() to simplify code.
> >
> > Signed-off-by: Yangtao Li <frank.li@vivo.com>
> > ---
> > v3:
> > -none
> > v2:
> > -convert to i_blockmask()
> > fs/ext4/inode.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> > index d251d705c276..eec36520e5e9 100644
> > --- a/fs/ext4/inode.c
> > +++ b/fs/ext4/inode.c
> > @@ -2218,7 +2218,7 @@ static int mpage_process_page_bufs(struct mpage_da_data *mpd,
> > {
> > struct inode *inode = mpd->inode;
> > int err;
> > - ext4_lblk_t blocks = (i_size_read(inode) + i_blocksize(inode) - 1)
> > + ext4_lblk_t blocks = (i_size_read(inode) + i_blockmask(inode))
> > >> inode->i_blkbits;
>
> Umm... That actually asks for DIV_ROUND_UP(i_size_read_inode(), i_blocksize(inode)) -
> compiler should bloody well be able to figure out that division by (1 << n) is
> shift down by n and it's easier to follow that way...
BTW, here the fact that you are adding the mask is misleading - it's true,
but we are not using it as a mask - it's straight arithmetics.
One can do an equivalent code where it would've been used as a mask, but that
would be harder to read -
(((i_size_read(inode) - 1) | i_blockmask(inode)) + 1) >> inode->i_blkbits
and I doubt anyone wants that kind of puzzles to stumble upon.
next prev parent reply other threads:[~2023-03-10 3:32 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-09 15:21 [PATCH v3 1/6] fs: add i_blockmask() Yangtao Li
2023-03-09 15:21 ` [Cluster-devel] " Yangtao Li
2023-03-09 15:21 ` [Ocfs2-devel] " Yangtao Li via Ocfs2-devel
2023-03-09 15:21 ` Yangtao Li
2023-03-09 15:21 ` [PATCH v3 2/6] erofs: convert to use i_blockmask() Yangtao Li
2023-03-09 15:21 ` [Cluster-devel] " Yangtao Li
2023-03-09 15:21 ` [Ocfs2-devel] " Yangtao Li via Ocfs2-devel
2023-03-09 15:21 ` Yangtao Li
2023-03-10 3:15 ` Al Viro
2023-03-10 3:15 ` [Cluster-devel] " Al Viro
2023-03-10 3:15 ` Al Viro
2023-03-10 3:15 ` [Ocfs2-devel] " Al Viro via Ocfs2-devel
2023-03-10 3:42 ` Gao Xiang
2023-03-10 3:42 ` [Cluster-devel] " Gao Xiang
2023-03-10 3:42 ` [Ocfs2-devel] " Gao Xiang via Ocfs2-devel
2023-03-10 3:42 ` Gao Xiang
2023-03-10 3:47 ` Gao Xiang
2023-03-10 3:47 ` [Cluster-devel] " Gao Xiang
2023-03-10 3:47 ` [Ocfs2-devel] " Gao Xiang via Ocfs2-devel
2023-03-10 3:47 ` Gao Xiang
2023-03-10 3:51 ` Yangtao Li
2023-03-10 3:51 ` [Cluster-devel] " Yangtao Li
2023-03-10 3:51 ` [Ocfs2-devel] " Yangtao Li via Ocfs2-devel
2023-03-10 3:51 ` Yangtao Li
2023-03-10 4:05 ` Al Viro
2023-03-10 4:05 ` [Cluster-devel] " Al Viro
2023-03-10 4:05 ` Al Viro
2023-03-10 4:05 ` [Ocfs2-devel] " Al Viro via Ocfs2-devel
2023-03-10 6:50 ` Yangtao Li
2023-03-10 6:50 ` [Cluster-devel] " Yangtao Li
2023-03-10 6:50 ` [Ocfs2-devel] " Yangtao Li via Ocfs2-devel
2023-03-10 6:50 ` Yangtao Li
2023-03-09 15:21 ` [PATCH v3 3/6] gfs2: " Yangtao Li
2023-03-09 15:21 ` [Cluster-devel] " Yangtao Li
2023-03-09 15:21 ` [Ocfs2-devel] " Yangtao Li via Ocfs2-devel
2023-03-09 15:21 ` Yangtao Li
2023-03-09 15:21 ` [PATCH v3 4/6] ext4: " Yangtao Li
2023-03-09 15:21 ` [Cluster-devel] " Yangtao Li
2023-03-09 15:21 ` [Ocfs2-devel] " Yangtao Li via Ocfs2-devel
2023-03-09 15:21 ` Yangtao Li
2023-03-10 3:19 ` Al Viro
2023-03-10 3:19 ` [Cluster-devel] " Al Viro
2023-03-10 3:19 ` Al Viro
2023-03-10 3:19 ` [Ocfs2-devel] " Al Viro via Ocfs2-devel
2023-03-10 3:32 ` Al Viro [this message]
2023-03-10 3:32 ` [Cluster-devel] " Al Viro
2023-03-10 3:32 ` Al Viro
2023-03-10 3:32 ` [Ocfs2-devel] " Al Viro via Ocfs2-devel
2023-03-09 15:21 ` [PATCH v3 5/6] ocfs2: " Yangtao Li
2023-03-09 15:21 ` [Cluster-devel] " Yangtao Li
2023-03-09 15:21 ` [Ocfs2-devel] " Yangtao Li via Ocfs2-devel
2023-03-09 15:21 ` Yangtao Li
2023-03-10 3:26 ` Al Viro
2023-03-10 3:26 ` [Cluster-devel] " Al Viro
2023-03-10 3:26 ` Al Viro
2023-03-10 3:26 ` [Ocfs2-devel] " Al Viro via Ocfs2-devel
2023-03-09 15:21 ` [PATCH v3 6/6] fs/remap_range: " Yangtao Li
2023-03-09 15:21 ` [Cluster-devel] " Yangtao Li
2023-03-09 15:21 ` [Ocfs2-devel] " Yangtao Li via Ocfs2-devel
2023-03-09 15:21 ` Yangtao Li
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