[PATCH] tmpfs: support SEEK_DATA and SEEK_HOLE (reprise)

[PATCH] tmpfs: support SEEK_DATA and SEEK_HOLE (reprise)

[Hugh Dickins]

Revert 3.5's f21f8062201f ("tmpfs: revert SEEK_DATA and SEEK_HOLE")
to reinstate 4fb5ef089b28 ("tmpfs: support SEEK_DATA and SEEK_HOLE"),
with the intervening additional arg to generic_file_llseek_size().

In 3.8, ext4 is expected to join btrfs, ocfs2 and xfs with proper
SEEK_DATA and SEEK_HOLE support; and a good case has now been made
for it on tmpfs, so let's join the party.

It's quite easy for tmpfs to scan the radix_tree to support llseek's new
SEEK_DATA and SEEK_HOLE options: so add them while the minutiae are still
on my mind (in particular, the !PageUptodate-ness of pages fallocated but
still unwritten).

[akpm@linux-foundation.org: fix warning with CONFIG_TMPFS=n]
Signed-off-by: Hugh Dickins <hughd@google.com>
---

 mm/shmem.c |   92 ++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 91 insertions(+), 1 deletion(-)

--- 3.7-rc7/mm/shmem.c	2012-11-16 19:26:56.388459961 -0800
+++ linux/mm/shmem.c	2012-11-28 15:53:38.788477201 -0800
@@ -1709,6 +1709,96 @@ static ssize_t shmem_file_splice_read(st
 	return error;
 }
 
+/*
+ * llseek SEEK_DATA or SEEK_HOLE through the radix_tree.
+ */
+static pgoff_t shmem_seek_hole_data(struct address_space *mapping,
+				    pgoff_t index, pgoff_t end, int origin)
+{
+	struct page *page;
+	struct pagevec pvec;
+	pgoff_t indices[PAGEVEC_SIZE];
+	bool done = false;
+	int i;
+
+	pagevec_init(&pvec, 0);
+	pvec.nr = 1;		/* start small: we may be there already */
+	while (!done) {
+		pvec.nr = shmem_find_get_pages_and_swap(mapping, index,
+					pvec.nr, pvec.pages, indices);
+		if (!pvec.nr) {
+			if (origin == SEEK_DATA)
+				index = end;
+			break;
+		}
+		for (i = 0; i < pvec.nr; i++, index++) {
+			if (index < indices[i]) {
+				if (origin == SEEK_HOLE) {
+					done = true;
+					break;
+				}
+				index = indices[i];
+			}
+			page = pvec.pages[i];
+			if (page && !radix_tree_exceptional_entry(page)) {
+				if (!PageUptodate(page))
+					page = NULL;
+			}
+			if (index >= end ||
+			    (page && origin == SEEK_DATA) ||
+			    (!page && origin == SEEK_HOLE)) {
+				done = true;
+				break;
+			}
+		}
+		shmem_deswap_pagevec(&pvec);
+		pagevec_release(&pvec);
+		pvec.nr = PAGEVEC_SIZE;
+		cond_resched();
+	}
+	return index;
+}
+
+static loff_t shmem_file_llseek(struct file *file, loff_t offset, int origin)
+{
+	struct address_space *mapping = file->f_mapping;
+	struct inode *inode = mapping->host;
+	pgoff_t start, end;
+	loff_t new_offset;
+
+	if (origin != SEEK_DATA && origin != SEEK_HOLE)
+		return generic_file_llseek_size(file, offset, origin,
+					MAX_LFS_FILESIZE, i_size_read(inode));
+	mutex_lock(&inode->i_mutex);
+	/* We're holding i_mutex so we can access i_size directly */
+
+	if (offset < 0)
+		offset = -EINVAL;
+	else if (offset >= inode->i_size)
+		offset = -ENXIO;
+	else {
+		start = offset >> PAGE_CACHE_SHIFT;
+		end = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+		new_offset = shmem_seek_hole_data(mapping, start, end, origin);
+		new_offset <<= PAGE_CACHE_SHIFT;
+		if (new_offset > offset) {
+			if (new_offset < inode->i_size)
+				offset = new_offset;
+			else if (origin == SEEK_DATA)
+				offset = -ENXIO;
+			else
+				offset = inode->i_size;
+		}
+	}
+
+	if (offset >= 0 && offset != file->f_pos) {
+		file->f_pos = offset;
+		file->f_version = 0;
+	}
+	mutex_unlock(&inode->i_mutex);
+	return offset;
+}
+
 static long shmem_fallocate(struct file *file, int mode, loff_t offset,
 							 loff_t len)
 {
@@ -2580,7 +2670,7 @@ static const struct address_space_operat
 static const struct file_operations shmem_file_operations = {
 	.mmap		= shmem_mmap,
 #ifdef CONFIG_TMPFS
-	.llseek		= generic_file_llseek,
+	.llseek		= shmem_file_llseek,
 	.read		= do_sync_read,
 	.write		= do_sync_write,
 	.aio_read	= shmem_file_aio_read,

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Re: [PATCH] tmpfs: support SEEK_DATA and SEEK_HOLE (reprise)

[Jaegeuk Hanse]

On Wed, Nov 28, 2012 at 05:22:03PM -0800, Hugh Dickins wrote:
>Revert 3.5's f21f8062201f ("tmpfs: revert SEEK_DATA and SEEK_HOLE")
>to reinstate 4fb5ef089b28 ("tmpfs: support SEEK_DATA and SEEK_HOLE"),
>with the intervening additional arg to generic_file_llseek_size().
>
>In 3.8, ext4 is expected to join btrfs, ocfs2 and xfs with proper
>SEEK_DATA and SEEK_HOLE support; and a good case has now been made
>for it on tmpfs, so let's join the party.
>

Hi Hugh,

IIUC, several months ago you revert the patch. You said, 

"I don't know who actually uses SEEK_DATA or SEEK_HOLE, and whether it
would be of any use to them on tmpfs.  This code adds 92 lines and 752
bytes on x86_64 - is that bloat or worthwhile?"

But this time in which scenario will use it?

Regards,
Jaegeuk

>It's quite easy for tmpfs to scan the radix_tree to support llseek's new
>SEEK_DATA and SEEK_HOLE options: so add them while the minutiae are still
>on my mind (in particular, the !PageUptodate-ness of pages fallocated but
>still unwritten).
>
>[akpm@linux-foundation.org: fix warning with CONFIG_TMPFS=n]
>Signed-off-by: Hugh Dickins <hughd@google.com>
>---
>
> mm/shmem.c |   92 ++++++++++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 91 insertions(+), 1 deletion(-)
>
>--- 3.7-rc7/mm/shmem.c	2012-11-16 19:26:56.388459961 -0800
>+++ linux/mm/shmem.c	2012-11-28 15:53:38.788477201 -0800
>@@ -1709,6 +1709,96 @@ static ssize_t shmem_file_splice_read(st
> 	return error;
> }
> 
>+/*
>+ * llseek SEEK_DATA or SEEK_HOLE through the radix_tree.
>+ */
>+static pgoff_t shmem_seek_hole_data(struct address_space *mapping,
>+				    pgoff_t index, pgoff_t end, int origin)
>+{
>+	struct page *page;
>+	struct pagevec pvec;
>+	pgoff_t indices[PAGEVEC_SIZE];
>+	bool done = false;
>+	int i;
>+
>+	pagevec_init(&pvec, 0);
>+	pvec.nr = 1;		/* start small: we may be there already */
>+	while (!done) {
>+		pvec.nr = shmem_find_get_pages_and_swap(mapping, index,
>+					pvec.nr, pvec.pages, indices);
>+		if (!pvec.nr) {
>+			if (origin == SEEK_DATA)
>+				index = end;
>+			break;
>+		}
>+		for (i = 0; i < pvec.nr; i++, index++) {
>+			if (index < indices[i]) {
>+				if (origin == SEEK_HOLE) {
>+					done = true;
>+					break;
>+				}
>+				index = indices[i];
>+			}
>+			page = pvec.pages[i];
>+			if (page && !radix_tree_exceptional_entry(page)) {
>+				if (!PageUptodate(page))
>+					page = NULL;
>+			}
>+			if (index >= end ||
>+			    (page && origin == SEEK_DATA) ||
>+			    (!page && origin == SEEK_HOLE)) {
>+				done = true;
>+				break;
>+			}
>+		}
>+		shmem_deswap_pagevec(&pvec);
>+		pagevec_release(&pvec);
>+		pvec.nr = PAGEVEC_SIZE;
>+		cond_resched();
>+	}
>+	return index;
>+}
>+
>+static loff_t shmem_file_llseek(struct file *file, loff_t offset, int origin)
>+{
>+	struct address_space *mapping = file->f_mapping;
>+	struct inode *inode = mapping->host;
>+	pgoff_t start, end;
>+	loff_t new_offset;
>+
>+	if (origin != SEEK_DATA && origin != SEEK_HOLE)
>+		return generic_file_llseek_size(file, offset, origin,
>+					MAX_LFS_FILESIZE, i_size_read(inode));
>+	mutex_lock(&inode->i_mutex);
>+	/* We're holding i_mutex so we can access i_size directly */
>+
>+	if (offset < 0)
>+		offset = -EINVAL;
>+	else if (offset >= inode->i_size)
>+		offset = -ENXIO;
>+	else {
>+		start = offset >> PAGE_CACHE_SHIFT;
>+		end = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
>+		new_offset = shmem_seek_hole_data(mapping, start, end, origin);
>+		new_offset <<= PAGE_CACHE_SHIFT;
>+		if (new_offset > offset) {
>+			if (new_offset < inode->i_size)
>+				offset = new_offset;
>+			else if (origin == SEEK_DATA)
>+				offset = -ENXIO;
>+			else
>+				offset = inode->i_size;
>+		}
>+	}
>+
>+	if (offset >= 0 && offset != file->f_pos) {
>+		file->f_pos = offset;
>+		file->f_version = 0;
>+	}
>+	mutex_unlock(&inode->i_mutex);
>+	return offset;
>+}
>+
> static long shmem_fallocate(struct file *file, int mode, loff_t offset,
> 							 loff_t len)
> {
>@@ -2580,7 +2670,7 @@ static const struct address_space_operat
> static const struct file_operations shmem_file_operations = {
> 	.mmap		= shmem_mmap,
> #ifdef CONFIG_TMPFS
>-	.llseek		= generic_file_llseek,
>+	.llseek		= shmem_file_llseek,
> 	.read		= do_sync_read,
> 	.write		= do_sync_write,
> 	.aio_read	= shmem_file_aio_read,
>
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Re: [PATCH] tmpfs: support SEEK_DATA and SEEK_HOLE (reprise)

[Hugh Dickins]

On Thu, 29 Nov 2012, Jaegeuk Hanse wrote:
> On Wed, Nov 28, 2012 at 05:22:03PM -0800, Hugh Dickins wrote:
> >Revert 3.5's f21f8062201f ("tmpfs: revert SEEK_DATA and SEEK_HOLE")
> >to reinstate 4fb5ef089b28 ("tmpfs: support SEEK_DATA and SEEK_HOLE"),
> >with the intervening additional arg to generic_file_llseek_size().
> >
> >In 3.8, ext4 is expected to join btrfs, ocfs2 and xfs with proper
> >SEEK_DATA and SEEK_HOLE support; and a good case has now been made
> >for it on tmpfs, so let's join the party.
> >
> 
> Hi Hugh,
> 
> IIUC, several months ago you revert the patch. You said, 
> 
> "I don't know who actually uses SEEK_DATA or SEEK_HOLE, and whether it
> would be of any use to them on tmpfs.  This code adds 92 lines and 752
> bytes on x86_64 - is that bloat or worthwhile?"

YUC.

> 
> But this time in which scenario will use it?

I was not very convinced by the grep argument from Jim and Paul:
that seemed to be grep holding on to a no-arbitrary-limits dogma,
at the expense of its users, causing an absurd line-length issue,
which use of SEEK_DATA happens to avoid in some cases.

The cp of sparse files from Jeff and Dave was more convincing;
but I still didn't see why little old tmpfs needed to be ahead
of the pack.

But at LinuxCon/Plumbers in San Diego in August, a more convincing
case was made: I was hoping you would not ask, because I did not take
notes, and cannot pass on the details - was it rpm building on tmpfs?
I was convinced enough to promise support on tmpfs when support on
ext4 goes in.

Hugh

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Re: [PATCH] tmpfs: support SEEK_DATA and SEEK_HOLE (reprise)

[Dave Chinner]

On Wed, Nov 28, 2012 at 05:22:03PM -0800, Hugh Dickins wrote:
> Revert 3.5's f21f8062201f ("tmpfs: revert SEEK_DATA and SEEK_HOLE")
> to reinstate 4fb5ef089b28 ("tmpfs: support SEEK_DATA and SEEK_HOLE"),
> with the intervening additional arg to generic_file_llseek_size().
> 
> In 3.8, ext4 is expected to join btrfs, ocfs2 and xfs with proper
> SEEK_DATA and SEEK_HOLE support; and a good case has now been made
> for it on tmpfs, so let's join the party.
> 
> It's quite easy for tmpfs to scan the radix_tree to support llseek's new
> SEEK_DATA and SEEK_HOLE options: so add them while the minutiae are still
> on my mind (in particular, the !PageUptodate-ness of pages fallocated but
> still unwritten).
> 
> [akpm@linux-foundation.org: fix warning with CONFIG_TMPFS=n]
> Signed-off-by: Hugh Dickins <hughd@google.com>
> ---

Does it pass the seek hole/data tests (285, 286) in xfstests?

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

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Re: [PATCH] tmpfs: support SEEK_DATA and SEEK_HOLE (reprise)

[Jim Meyering]

Hugh Dickins wrote:
> On Thu, 29 Nov 2012, Jaegeuk Hanse wrote:
...
>> But this time in which scenario will use it?
>
> I was not very convinced by the grep argument from Jim and Paul:
> that seemed to be grep holding on to a no-arbitrary-limits dogma,
> at the expense of its users, causing an absurd line-length issue,
> which use of SEEK_DATA happens to avoid in some cases.
>
> The cp of sparse files from Jeff and Dave was more convincing;
> but I still didn't see why little old tmpfs needed to be ahead
> of the pack.
>
> But at LinuxCon/Plumbers in San Diego in August, a more convincing
> case was made: I was hoping you would not ask, because I did not take
> notes, and cannot pass on the details - was it rpm building on tmpfs?
> I was convinced enough to promise support on tmpfs when support on
> ext4 goes in.

Re the cp-vs-sparse-file case, the current FIEMAP-based code in GNU
cp is ugly and complicated enough that until recently it harbored a
hard-to-reproduce data-corrupting bug[*].  Now that SEEK_DATA/SEEK_HOLE
support work will work also for tmpfs and ext4, we can plan to remove
the FIEMAP-based code in favor of a simpler SEEK_DATA/SEEK_HOLE-based
implementation.

With the rise of virtualization, copying sparse images efficiently
(probably searching, too) is becoming more and more important.

So, yes, GNU cp will soon use this feature.

[*] https://plus.google.com/u/0/114228401647637059102/posts/FDV3JEaYsKD

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Re: [PATCH] tmpfs: support SEEK_DATA and SEEK_HOLE (reprise)

[Hugh Dickins]

On Thu, 29 Nov 2012, Dave Chinner wrote:
> On Wed, Nov 28, 2012 at 05:22:03PM -0800, Hugh Dickins wrote:
> > Revert 3.5's f21f8062201f ("tmpfs: revert SEEK_DATA and SEEK_HOLE")
> > to reinstate 4fb5ef089b28 ("tmpfs: support SEEK_DATA and SEEK_HOLE"),
> > with the intervening additional arg to generic_file_llseek_size().
> > 
> > In 3.8, ext4 is expected to join btrfs, ocfs2 and xfs with proper
> > SEEK_DATA and SEEK_HOLE support; and a good case has now been made
> > for it on tmpfs, so let's join the party.
> > 
> > It's quite easy for tmpfs to scan the radix_tree to support llseek's new
> > SEEK_DATA and SEEK_HOLE options: so add them while the minutiae are still
> > on my mind (in particular, the !PageUptodate-ness of pages fallocated but
> > still unwritten).
> > 
> > [akpm@linux-foundation.org: fix warning with CONFIG_TMPFS=n]
> > Signed-off-by: Hugh Dickins <hughd@google.com>
> > ---
> 
> Does it pass the seek hole/data tests (285, 286) in xfstests?

It did before and ... [install this, install that, install tother]
... yes, it still passes those tests - using Boris Ranto's patch
extending xfstests to include tmpfs.

Though I'd have even more confidence if they gave a little pat on
the back for doing better than the no-op default, which also passes.

Hugh

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Re: [PATCH] tmpfs: support SEEK_DATA and SEEK_HOLE (reprise)

[Jeff Liu]

On 11/29/2012 12:15 PM, Jim Meyering wrote:
> Hugh Dickins wrote:
>> On Thu, 29 Nov 2012, Jaegeuk Hanse wrote:
> ...
>>> But this time in which scenario will use it?
>>
>> I was not very convinced by the grep argument from Jim and Paul:
>> that seemed to be grep holding on to a no-arbitrary-limits dogma,
>> at the expense of its users, causing an absurd line-length issue,
>> which use of SEEK_DATA happens to avoid in some cases.
>>
>> The cp of sparse files from Jeff and Dave was more convincing;
>> but I still didn't see why little old tmpfs needed to be ahead
>> of the pack.
>>
>> But at LinuxCon/Plumbers in San Diego in August, a more convincing
>> case was made: I was hoping you would not ask, because I did not take
>> notes, and cannot pass on the details - was it rpm building on tmpfs?
>> I was convinced enough to promise support on tmpfs when support on
>> ext4 goes in.
> 
> Re the cp-vs-sparse-file case, the current FIEMAP-based code in GNU
> cp is ugly and complicated enough that until recently it harbored a
> hard-to-reproduce data-corrupting bug[*].  Now that SEEK_DATA/SEEK_HOLE
> support work will work also for tmpfs and ext4, we can plan to remove
> the FIEMAP-based code in favor of a simpler SEEK_DATA/SEEK_HOLE-based
> implementation.
How do we teach du(1) to aware of the real disk footprint with Btrfs
clone or OCFS2 reflinked files if we remove the FIEMAP-based code?

How about if we still keep it there, and introduce SEEK_DATA/SEEK_HOLE
code to the extent-scan module which is dedicated to deal with sparse files?

Thanks,
-Jeff
> 
> With the rise of virtualization, copying sparse images efficiently
> (probably searching, too) is becoming more and more important.
> 
> So, yes, GNU cp will soon use this feature.
> 
> [*] https://plus.google.com/u/0/114228401647637059102/posts/FDV3JEaYsKD
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Re: [PATCH] tmpfs: support SEEK_DATA and SEEK_HOLE (reprise)

[Jim Meyering]

Jeff Liu wrote:

> On 11/29/2012 12:15 PM, Jim Meyering wrote:
>> Hugh Dickins wrote:
>>> On Thu, 29 Nov 2012, Jaegeuk Hanse wrote:
>> ...
>>>> But this time in which scenario will use it?
>>>
>>> I was not very convinced by the grep argument from Jim and Paul:
>>> that seemed to be grep holding on to a no-arbitrary-limits dogma,
>>> at the expense of its users, causing an absurd line-length issue,
>>> which use of SEEK_DATA happens to avoid in some cases.
>>>
>>> The cp of sparse files from Jeff and Dave was more convincing;
>>> but I still didn't see why little old tmpfs needed to be ahead
>>> of the pack.
>>>
>>> But at LinuxCon/Plumbers in San Diego in August, a more convincing
>>> case was made: I was hoping you would not ask, because I did not take
>>> notes, and cannot pass on the details - was it rpm building on tmpfs?
>>> I was convinced enough to promise support on tmpfs when support on
>>> ext4 goes in.
>>
>> Re the cp-vs-sparse-file case, the current FIEMAP-based code in GNU
>> cp is ugly and complicated enough that until recently it harbored a
>> hard-to-reproduce data-corrupting bug[*].  Now that SEEK_DATA/SEEK_HOLE
>> support work will work also for tmpfs and ext4, we can plan to remove
>> the FIEMAP-based code in favor of a simpler SEEK_DATA/SEEK_HOLE-based
>> implementation.
> How do we teach du(1) to aware of the real disk footprint with Btrfs
> clone or OCFS2 reflinked files if we remove the FIEMAP-based code?
>
> How about if we still keep it there, and introduce SEEK_DATA/SEEK_HOLE
> code to the extent-scan module which is dedicated to deal with sparse files?

Hi Jeff,
By "removing the FIEMAP-based code" I mean the uses in copy.c.
All of that should remain independent of how du does its job,
so if FIEMAP is required for your planned du enhancement,
then feel free to use it.

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Re: [PATCH] tmpfs: support SEEK_DATA and SEEK_HOLE (reprise)

[Jeff Liu]

On 11/29/2012 02:53 PM, Jim Meyering wrote:
> Jeff Liu wrote:
> 
>> On 11/29/2012 12:15 PM, Jim Meyering wrote:
>>> Hugh Dickins wrote:
>>>> On Thu, 29 Nov 2012, Jaegeuk Hanse wrote:
>>> ...
>>>>> But this time in which scenario will use it?
>>>>
>>>> I was not very convinced by the grep argument from Jim and Paul:
>>>> that seemed to be grep holding on to a no-arbitrary-limits dogma,
>>>> at the expense of its users, causing an absurd line-length issue,
>>>> which use of SEEK_DATA happens to avoid in some cases.
>>>>
>>>> The cp of sparse files from Jeff and Dave was more convincing;
>>>> but I still didn't see why little old tmpfs needed to be ahead
>>>> of the pack.
>>>>
>>>> But at LinuxCon/Plumbers in San Diego in August, a more convincing
>>>> case was made: I was hoping you would not ask, because I did not take
>>>> notes, and cannot pass on the details - was it rpm building on tmpfs?
>>>> I was convinced enough to promise support on tmpfs when support on
>>>> ext4 goes in.
>>>
>>> Re the cp-vs-sparse-file case, the current FIEMAP-based code in GNU
>>> cp is ugly and complicated enough that until recently it harbored a
>>> hard-to-reproduce data-corrupting bug[*].  Now that SEEK_DATA/SEEK_HOLE
>>> support work will work also for tmpfs and ext4, we can plan to remove
>>> the FIEMAP-based code in favor of a simpler SEEK_DATA/SEEK_HOLE-based
>>> implementation.
>> How do we teach du(1) to aware of the real disk footprint with Btrfs
>> clone or OCFS2 reflinked files if we remove the FIEMAP-based code?
>>
>> How about if we still keep it there, and introduce SEEK_DATA/SEEK_HOLE
>> code to the extent-scan module which is dedicated to deal with sparse files?
> 
> Hi Jeff,
> By "removing the FIEMAP-based code" I mean the uses in copy.c.
> All of that should remain independent of how du does its job,
> so if FIEMAP is required for your planned du enhancement,
> then feel free to use it.
Hi Jim,
Thanks for the clarification, that's fine. :)

Regards,
-Jeff
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Re: [PATCH] tmpfs: support SEEK_DATA and SEEK_HOLE (reprise)

[Dave Chinner]

On Thu, Nov 29, 2012 at 05:15:50AM +0100, Jim Meyering wrote:
> Hugh Dickins wrote:
> > On Thu, 29 Nov 2012, Jaegeuk Hanse wrote:
> ...
> >> But this time in which scenario will use it?
> >
> > I was not very convinced by the grep argument from Jim and Paul:
> > that seemed to be grep holding on to a no-arbitrary-limits dogma,
> > at the expense of its users, causing an absurd line-length issue,
> > which use of SEEK_DATA happens to avoid in some cases.
> >
> > The cp of sparse files from Jeff and Dave was more convincing;
> > but I still didn't see why little old tmpfs needed to be ahead
> > of the pack.
> >
> > But at LinuxCon/Plumbers in San Diego in August, a more convincing
> > case was made: I was hoping you would not ask, because I did not take
> > notes, and cannot pass on the details - was it rpm building on tmpfs?
> > I was convinced enough to promise support on tmpfs when support on
> > ext4 goes in.
> 
> Re the cp-vs-sparse-file case, the current FIEMAP-based code in GNU
> cp is ugly and complicated enough that until recently it harbored a
> hard-to-reproduce data-corrupting bug[*].  Now that SEEK_DATA/SEEK_HOLE
> support work will work also for tmpfs and ext4, we can plan to remove
> the FIEMAP-based code in favor of a simpler SEEK_DATA/SEEK_HOLE-based
> implementation.
> 
> With the rise of virtualization, copying sparse images efficiently
> (probably searching, too) is becoming more and more important.
> 
> So, yes, GNU cp will soon use this feature.

It would be nice if utilities like grep used it, too, because having
grep burn gigabytes of memory scanning holes in large files and
then going OOM is, well, kind of nasty:

$ xfs_io -f -c "truncate 1t" blah
$ ls -l
total 0
-rw-r--r-- 1 dave dave 1.0T Nov 30 06:42 blah
$ grep foo blah
grep: memory exhausted
$ $ grep -V
grep (GNU grep) 2.12
....

It looks like it's doing something silly when holes are found - the
buffer size just keeps getting doubled until it's larger than
physical memory (4GB in this case).

openat(AT_FDCWD, "blah", O_RDONLY)      = 3
fstat(3, {st_mode=S_IFREG|0600, st_size=1099511627776, ...}) = 0
ioctl(3, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7ffff31d4c80) = -1 ENOTTY (Inappropriate ioctl for device)
read(3, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 32768) = 32768
read(3, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 32768) = 32768
mmap(NULL, 139264, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f62b0291000
read(3, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 65536) = 65536
mmap(NULL, 270336, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f62b024f000
munmap(0x7f62b0291000, 139264)          = 0
read(3, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 131072) = 131072
mmap(NULL, 532480, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f62afc0d000
munmap(0x7f62b024f000, 270336)          = 0
read(3, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 262144) = 262144
mmap(NULL, 1056768, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f62afb0b000
munmap(0x7f62afc0d000, 532480)          = 0
read(3, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 524288) = 524288
mmap(NULL, 2105344, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f62af909000
munmap(0x7f62afb0b000, 1056768)         = 0
read(3, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 1048576) = 1048576
mmap(NULL, 4202496, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f62af507000
munmap(0x7f62af909000, 2105344)         = 0
read(3, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 2097152) = 2097152
mmap(NULL, 8396800, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f62aed05000
munmap(0x7f62af507000, 4202496)         = 0
read(3, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 4194304) = 4194304
mmap(NULL, 16785408, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f62add03000
munmap(0x7f62aed05000, 8396800)         = 0
read(3, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 8388608) = 8388608
mmap(NULL, 33562624, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f62abd01000
munmap(0x7f62add03000, 16785408)        = 0
read(3, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 16777216) = 16777216
mmap(NULL, 67117056, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f62a7cff000
munmap(0x7f62abd01000, 33562624)        = 0
read(3, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 33554432) = 33554432
mmap(NULL, 134225920, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f629fcfd000
munmap(0x7f62a7cff000, 67117056)        = 0
read(3, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 67108864) = 67108864
mmap(NULL, 268443648, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f628fcfb000
munmap(0x7f629fcfd000, 134225920)       = 0
read(3, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 134217728) = 134217728
mmap(NULL, 536879104, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f626fcf9000
munmap(0x7f628fcfb000, 268443648)       = 0
read(3, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 268435456) = 268435456
mmap(NULL, 1073750016, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f622fcf7000
munmap(0x7f626fcf9000, 536879104)       = 0
read(3, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 536870912) = 536870912
mmap(NULL, 2147491840, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f61afcf5000
munmap(0x7f622fcf7000, 1073750016)      = 0
read(3, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 1073741824) = 1073741824
mmap(NULL, 4294975488, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f60afcf3000
munmap(0x7f61afcf5000, 2147491840)      = 0
read(3, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 2147483648) = 2147479552
read(3, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 4096) = 4096
mmap(NULL, 8589942784, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = -1 ENOMEM (Cannot allocate memory)

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

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Re: [PATCH] tmpfs: support SEEK_DATA and SEEK_HOLE (reprise)

[Jim Meyering]

Dave Chinner wrote:
...
>> So, yes, GNU cp will soon use this feature.
>
> It would be nice if utilities like grep used it, too, because having
> grep burn gigabytes of memory scanning holes in large files and
> then going OOM is, well, kind of nasty:
>
> $ xfs_io -f -c "truncate 1t" blah
> $ ls -l
> total 0
> -rw-r--r-- 1 dave dave 1.0T Nov 30 06:42 blah
> $ grep foo blah
> grep: memory exhausted
> $ $ grep -V
> grep (GNU grep) 2.12

Hi Dave,

Yes, adapting grep is also on the road map.
That precise case was one of my arguments for making SEEK_DATA/SEEK_HOLE
support more widespread.

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Re: [PATCH] tmpfs: support SEEK_DATA and SEEK_HOLE (reprise)

[Andrew Morton]

On Wed, 28 Nov 2012 17:22:03 -0800 (PST)
Hugh Dickins <hughd@google.com> wrote:

> Revert 3.5's f21f8062201f ("tmpfs: revert SEEK_DATA and SEEK_HOLE")
> to reinstate 4fb5ef089b28 ("tmpfs: support SEEK_DATA and SEEK_HOLE"),
> with the intervening additional arg to generic_file_llseek_size().
> 
> In 3.8, ext4 is expected to join btrfs, ocfs2 and xfs with proper
> SEEK_DATA and SEEK_HOLE support; and a good case has now been made
> for it on tmpfs, so let's join the party.
> 
> It's quite easy for tmpfs to scan the radix_tree to support llseek's new
> SEEK_DATA and SEEK_HOLE options: so add them while the minutiae are still
> on my mind (in particular, the !PageUptodate-ness of pages fallocated but
> still unwritten).
> 
> ...
>

> +/*
> + * llseek SEEK_DATA or SEEK_HOLE through the radix_tree.
> + */
> +static pgoff_t shmem_seek_hole_data(struct address_space *mapping,
> +				    pgoff_t index, pgoff_t end, int origin)

So I was starting at this wondering what on earth "origin" is and why
it has the fishy-in-this-context type "int".

There is a pretty well established convention that the lseek seek mode
is called "whence".

The below gets most of it.  Too anal?


From: Andrew Morton <akpm@linux-foundation.org>
Subject: lseek: the "whence" argument is called "whence"

But the kernel decided to call it "origin" instead.  Fix most of the
sites.

Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 fs/bad_inode.c           |    2 -
 fs/block_dev.c           |    4 +--
 fs/btrfs/file.c          |   16 +++++++-------
 fs/ceph/dir.c            |    4 +--
 fs/ceph/file.c           |    6 ++---
 fs/cifs/cifsfs.c         |    8 +++----
 fs/configfs/dir.c        |    4 +--
 fs/ext3/dir.c            |    6 ++---
 fs/ext4/dir.c            |    6 ++---
 fs/ext4/file.c           |   22 ++++++++++----------
 fs/fuse/file.c           |    8 +++----
 fs/gfs2/file.c           |   10 ++++-----
 fs/libfs.c               |    4 +--
 fs/nfs/dir.c             |    6 ++---
 fs/nfs/file.c            |   10 ++++-----
 fs/ocfs2/extent_map.c    |   12 +++++------
 fs/ocfs2/file.c          |    6 ++---
 fs/pstore/inode.c        |    6 ++---
 fs/read_write.c          |   40 ++++++++++++++++++-------------------
 fs/seq_file.c            |    4 +--
 fs/ubifs/dir.c           |    4 +--
 include/linux/fs.h       |   12 +++++------
 include/linux/ftrace.h   |    4 +--
 include/linux/syscalls.h |    4 +--
 kernel/trace/ftrace.c    |    4 +--
 mm/shmem.c               |   20 +++++++++---------
 26 files changed, 116 insertions(+), 116 deletions(-)

diff -puN fs/read_write.c~lseek-the-whence-argument-is-called-whence fs/read_write.c
--- a/fs/read_write.c~lseek-the-whence-argument-is-called-whence
+++ a/fs/read_write.c
@@ -54,7 +54,7 @@ static loff_t lseek_execute(struct file 
  * generic_file_llseek_size - generic llseek implementation for regular files
  * @file:	file structure to seek on
  * @offset:	file offset to seek to
- * @origin:	type of seek
+ * @whence:	type of seek
  * @size:	max size of this file in file system
  * @eof:	offset used for SEEK_END position
  *
@@ -67,12 +67,12 @@ static loff_t lseek_execute(struct file 
  * read/writes behave like SEEK_SET against seeks.
  */
 loff_t
-generic_file_llseek_size(struct file *file, loff_t offset, int origin,
+generic_file_llseek_size(struct file *file, loff_t offset, int whence,
 		loff_t maxsize, loff_t eof)
 {
 	struct inode *inode = file->f_mapping->host;
 
-	switch (origin) {
+	switch (whence) {
 	case SEEK_END:
 		offset += eof;
 		break;
@@ -122,17 +122,17 @@ EXPORT_SYMBOL(generic_file_llseek_size);
  * generic_file_llseek - generic llseek implementation for regular files
  * @file:	file structure to seek on
  * @offset:	file offset to seek to
- * @origin:	type of seek
+ * @whence:	type of seek
  *
  * This is a generic implemenation of ->llseek useable for all normal local
  * filesystems.  It just updates the file offset to the value specified by
- * @offset and @origin under i_mutex.
+ * @offset and @whence under i_mutex.
  */
-loff_t generic_file_llseek(struct file *file, loff_t offset, int origin)
+loff_t generic_file_llseek(struct file *file, loff_t offset, int whence)
 {
 	struct inode *inode = file->f_mapping->host;
 
-	return generic_file_llseek_size(file, offset, origin,
+	return generic_file_llseek_size(file, offset, whence,
 					inode->i_sb->s_maxbytes,
 					i_size_read(inode));
 }
@@ -142,32 +142,32 @@ EXPORT_SYMBOL(generic_file_llseek);
  * noop_llseek - No Operation Performed llseek implementation
  * @file:	file structure to seek on
  * @offset:	file offset to seek to
- * @origin:	type of seek
+ * @whence:	type of seek
  *
  * This is an implementation of ->llseek useable for the rare special case when
  * userspace expects the seek to succeed but the (device) file is actually not
  * able to perform the seek. In this case you use noop_llseek() instead of
  * falling back to the default implementation of ->llseek.
  */
-loff_t noop_llseek(struct file *file, loff_t offset, int origin)
+loff_t noop_llseek(struct file *file, loff_t offset, int whence)
 {
 	return file->f_pos;
 }
 EXPORT_SYMBOL(noop_llseek);
 
-loff_t no_llseek(struct file *file, loff_t offset, int origin)
+loff_t no_llseek(struct file *file, loff_t offset, int whence)
 {
 	return -ESPIPE;
 }
 EXPORT_SYMBOL(no_llseek);
 
-loff_t default_llseek(struct file *file, loff_t offset, int origin)
+loff_t default_llseek(struct file *file, loff_t offset, int whence)
 {
 	struct inode *inode = file->f_path.dentry->d_inode;
 	loff_t retval;
 
 	mutex_lock(&inode->i_mutex);
-	switch (origin) {
+	switch (whence) {
 		case SEEK_END:
 			offset += i_size_read(inode);
 			break;
@@ -216,7 +216,7 @@ out:
 }
 EXPORT_SYMBOL(default_llseek);
 
-loff_t vfs_llseek(struct file *file, loff_t offset, int origin)
+loff_t vfs_llseek(struct file *file, loff_t offset, int whence)
 {
 	loff_t (*fn)(struct file *, loff_t, int);
 
@@ -225,11 +225,11 @@ loff_t vfs_llseek(struct file *file, lof
 		if (file->f_op && file->f_op->llseek)
 			fn = file->f_op->llseek;
 	}
-	return fn(file, offset, origin);
+	return fn(file, offset, whence);
 }
 EXPORT_SYMBOL(vfs_llseek);
 
-SYSCALL_DEFINE3(lseek, unsigned int, fd, off_t, offset, unsigned int, origin)
+SYSCALL_DEFINE3(lseek, unsigned int, fd, off_t, offset, unsigned int, whence)
 {
 	off_t retval;
 	struct fd f = fdget(fd);
@@ -237,8 +237,8 @@ SYSCALL_DEFINE3(lseek, unsigned int, fd,
 		return -EBADF;
 
 	retval = -EINVAL;
-	if (origin <= SEEK_MAX) {
-		loff_t res = vfs_llseek(f.file, offset, origin);
+	if (whence <= SEEK_MAX) {
+		loff_t res = vfs_llseek(f.file, offset, whence);
 		retval = res;
 		if (res != (loff_t)retval)
 			retval = -EOVERFLOW;	/* LFS: should only happen on 32 bit platforms */
@@ -250,7 +250,7 @@ SYSCALL_DEFINE3(lseek, unsigned int, fd,
 #ifdef __ARCH_WANT_SYS_LLSEEK
 SYSCALL_DEFINE5(llseek, unsigned int, fd, unsigned long, offset_high,
 		unsigned long, offset_low, loff_t __user *, result,
-		unsigned int, origin)
+		unsigned int, whence)
 {
 	int retval;
 	struct fd f = fdget(fd);
@@ -260,11 +260,11 @@ SYSCALL_DEFINE5(llseek, unsigned int, fd
 		return -EBADF;
 
 	retval = -EINVAL;
-	if (origin > SEEK_MAX)
+	if (whence > SEEK_MAX)
 		goto out_putf;
 
 	offset = vfs_llseek(f.file, ((loff_t) offset_high << 32) | offset_low,
-			origin);
+			whence);
 
 	retval = (int)offset;
 	if (offset >= 0) {
diff -puN include/linux/fs.h~lseek-the-whence-argument-is-called-whence include/linux/fs.h
--- a/include/linux/fs.h~lseek-the-whence-argument-is-called-whence
+++ a/include/linux/fs.h
@@ -2291,9 +2291,9 @@ extern ino_t find_inode_number(struct de
 #include <linux/err.h>
 
 /* needed for stackable file system support */
-extern loff_t default_llseek(struct file *file, loff_t offset, int origin);
+extern loff_t default_llseek(struct file *file, loff_t offset, int whence);
 
-extern loff_t vfs_llseek(struct file *file, loff_t offset, int origin);
+extern loff_t vfs_llseek(struct file *file, loff_t offset, int whence);
 
 extern int inode_init_always(struct super_block *, struct inode *);
 extern void inode_init_once(struct inode *);
@@ -2403,11 +2403,11 @@ extern long do_splice_direct(struct file
 
 extern void
 file_ra_state_init(struct file_ra_state *ra, struct address_space *mapping);
-extern loff_t noop_llseek(struct file *file, loff_t offset, int origin);
-extern loff_t no_llseek(struct file *file, loff_t offset, int origin);
-extern loff_t generic_file_llseek(struct file *file, loff_t offset, int origin);
+extern loff_t noop_llseek(struct file *file, loff_t offset, int whence);
+extern loff_t no_llseek(struct file *file, loff_t offset, int whence);
+extern loff_t generic_file_llseek(struct file *file, loff_t offset, int whence);
 extern loff_t generic_file_llseek_size(struct file *file, loff_t offset,
-		int origin, loff_t maxsize, loff_t eof);
+		int whence, loff_t maxsize, loff_t eof);
 extern int generic_file_open(struct inode * inode, struct file * filp);
 extern int nonseekable_open(struct inode * inode, struct file * filp);
 
diff -puN mm/shmem.c~lseek-the-whence-argument-is-called-whence mm/shmem.c
--- a/mm/shmem.c~lseek-the-whence-argument-is-called-whence
+++ a/mm/shmem.c
@@ -1714,7 +1714,7 @@ static ssize_t shmem_file_splice_read(st
  * llseek SEEK_DATA or SEEK_HOLE through the radix_tree.
  */
 static pgoff_t shmem_seek_hole_data(struct address_space *mapping,
-				    pgoff_t index, pgoff_t end, int origin)
+				    pgoff_t index, pgoff_t end, int whence)
 {
 	struct page *page;
 	struct pagevec pvec;
@@ -1728,13 +1728,13 @@ static pgoff_t shmem_seek_hole_data(stru
 		pvec.nr = shmem_find_get_pages_and_swap(mapping, index,
 					pvec.nr, pvec.pages, indices);
 		if (!pvec.nr) {
-			if (origin == SEEK_DATA)
+			if (whence == SEEK_DATA)
 				index = end;
 			break;
 		}
 		for (i = 0; i < pvec.nr; i++, index++) {
 			if (index < indices[i]) {
-				if (origin == SEEK_HOLE) {
+				if (whence == SEEK_HOLE) {
 					done = true;
 					break;
 				}
@@ -1746,8 +1746,8 @@ static pgoff_t shmem_seek_hole_data(stru
 					page = NULL;
 			}
 			if (index >= end ||
-			    (page && origin == SEEK_DATA) ||
-			    (!page && origin == SEEK_HOLE)) {
+			    (page && whence == SEEK_DATA) ||
+			    (!page && whence == SEEK_HOLE)) {
 				done = true;
 				break;
 			}
@@ -1760,15 +1760,15 @@ static pgoff_t shmem_seek_hole_data(stru
 	return index;
 }
 
-static loff_t shmem_file_llseek(struct file *file, loff_t offset, int origin)
+static loff_t shmem_file_llseek(struct file *file, loff_t offset, int whence)
 {
 	struct address_space *mapping = file->f_mapping;
 	struct inode *inode = mapping->host;
 	pgoff_t start, end;
 	loff_t new_offset;
 
-	if (origin != SEEK_DATA && origin != SEEK_HOLE)
-		return generic_file_llseek_size(file, offset, origin,
+	if (whence != SEEK_DATA && whence != SEEK_HOLE)
+		return generic_file_llseek_size(file, offset, whence,
 					MAX_LFS_FILESIZE, i_size_read(inode));
 	mutex_lock(&inode->i_mutex);
 	/* We're holding i_mutex so we can access i_size directly */
@@ -1780,12 +1780,12 @@ static loff_t shmem_file_llseek(struct f
 	else {
 		start = offset >> PAGE_CACHE_SHIFT;
 		end = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
-		new_offset = shmem_seek_hole_data(mapping, start, end, origin);
+		new_offset = shmem_seek_hole_data(mapping, start, end, whence);
 		new_offset <<= PAGE_CACHE_SHIFT;
 		if (new_offset > offset) {
 			if (new_offset < inode->i_size)
 				offset = new_offset;
-			else if (origin == SEEK_DATA)
+			else if (whence == SEEK_DATA)
 				offset = -ENXIO;
 			else
 				offset = inode->i_size;
diff -puN fs/bad_inode.c~lseek-the-whence-argument-is-called-whence fs/bad_inode.c
--- a/fs/bad_inode.c~lseek-the-whence-argument-is-called-whence
+++ a/fs/bad_inode.c
@@ -16,7 +16,7 @@
 #include <linux/poll.h>
 
 
-static loff_t bad_file_llseek(struct file *file, loff_t offset, int origin)
+static loff_t bad_file_llseek(struct file *file, loff_t offset, int whence)
 {
 	return -EIO;
 }
diff -puN fs/block_dev.c~lseek-the-whence-argument-is-called-whence fs/block_dev.c
--- a/fs/block_dev.c~lseek-the-whence-argument-is-called-whence
+++ a/fs/block_dev.c
@@ -392,7 +392,7 @@ static int blkdev_write_end(struct file 
  * for a block special file file->f_path.dentry->d_inode->i_size is zero
  * so we compute the size by hand (just as in block_read/write above)
  */
-static loff_t block_llseek(struct file *file, loff_t offset, int origin)
+static loff_t block_llseek(struct file *file, loff_t offset, int whence)
 {
 	struct inode *bd_inode = file->f_mapping->host;
 	loff_t size;
@@ -402,7 +402,7 @@ static loff_t block_llseek(struct file *
 	size = i_size_read(bd_inode);
 
 	retval = -EINVAL;
-	switch (origin) {
+	switch (whence) {
 		case SEEK_END:
 			offset += size;
 			break;
diff -puN fs/libfs.c~lseek-the-whence-argument-is-called-whence fs/libfs.c
--- a/fs/libfs.c~lseek-the-whence-argument-is-called-whence
+++ a/fs/libfs.c
@@ -81,11 +81,11 @@ int dcache_dir_close(struct inode *inode
 	return 0;
 }
 
-loff_t dcache_dir_lseek(struct file *file, loff_t offset, int origin)
+loff_t dcache_dir_lseek(struct file *file, loff_t offset, int whence)
 {
 	struct dentry *dentry = file->f_path.dentry;
 	mutex_lock(&dentry->d_inode->i_mutex);
-	switch (origin) {
+	switch (whence) {
 		case 1:
 			offset += file->f_pos;
 		case 0:
diff -puN fs/seq_file.c~lseek-the-whence-argument-is-called-whence fs/seq_file.c
--- a/fs/seq_file.c~lseek-the-whence-argument-is-called-whence
+++ a/fs/seq_file.c
@@ -300,14 +300,14 @@ EXPORT_SYMBOL(seq_read);
  *
  *	Ready-made ->f_op->llseek()
  */
-loff_t seq_lseek(struct file *file, loff_t offset, int origin)
+loff_t seq_lseek(struct file *file, loff_t offset, int whence)
 {
 	struct seq_file *m = file->private_data;
 	loff_t retval = -EINVAL;
 
 	mutex_lock(&m->lock);
 	m->version = file->f_version;
-	switch (origin) {
+	switch (whence) {
 		case 1:
 			offset += file->f_pos;
 		case 0:
diff -puN include/linux/ftrace.h~lseek-the-whence-argument-is-called-whence include/linux/ftrace.h
--- a/include/linux/ftrace.h~lseek-the-whence-argument-is-called-whence
+++ a/include/linux/ftrace.h
@@ -394,7 +394,7 @@ ssize_t ftrace_filter_write(struct file 
 			    size_t cnt, loff_t *ppos);
 ssize_t ftrace_notrace_write(struct file *file, const char __user *ubuf,
 			     size_t cnt, loff_t *ppos);
-loff_t ftrace_regex_lseek(struct file *file, loff_t offset, int origin);
+loff_t ftrace_regex_lseek(struct file *file, loff_t offset, int whence);
 int ftrace_regex_release(struct inode *inode, struct file *file);
 
 void __init
@@ -559,7 +559,7 @@ static inline ssize_t ftrace_filter_writ
 			    size_t cnt, loff_t *ppos) { return -ENODEV; }
 static inline ssize_t ftrace_notrace_write(struct file *file, const char __user *ubuf,
 			     size_t cnt, loff_t *ppos) { return -ENODEV; }
-static inline loff_t ftrace_regex_lseek(struct file *file, loff_t offset, int origin)
+static inline loff_t ftrace_regex_lseek(struct file *file, loff_t offset, int whence)
 {
 	return -ENODEV;
 }
diff -puN include/linux/syscalls.h~lseek-the-whence-argument-is-called-whence include/linux/syscalls.h
--- a/include/linux/syscalls.h~lseek-the-whence-argument-is-called-whence
+++ a/include/linux/syscalls.h
@@ -560,10 +560,10 @@ asmlinkage long sys_utime(char __user *f
 asmlinkage long sys_utimes(char __user *filename,
 				struct timeval __user *utimes);
 asmlinkage long sys_lseek(unsigned int fd, off_t offset,
-			  unsigned int origin);
+			  unsigned int whence);
 asmlinkage long sys_llseek(unsigned int fd, unsigned long offset_high,
 			unsigned long offset_low, loff_t __user *result,
-			unsigned int origin);
+			unsigned int whence);
 asmlinkage long sys_read(unsigned int fd, char __user *buf, size_t count);
 asmlinkage long sys_readahead(int fd, loff_t offset, size_t count);
 asmlinkage long sys_readv(unsigned long fd,
diff -puN kernel/trace/ftrace.c~lseek-the-whence-argument-is-called-whence kernel/trace/ftrace.c
--- a/kernel/trace/ftrace.c~lseek-the-whence-argument-is-called-whence
+++ a/kernel/trace/ftrace.c
@@ -2675,12 +2675,12 @@ ftrace_notrace_open(struct inode *inode,
 }
 
 loff_t
-ftrace_regex_lseek(struct file *file, loff_t offset, int origin)
+ftrace_regex_lseek(struct file *file, loff_t offset, int whence)
 {
 	loff_t ret;
 
 	if (file->f_mode & FMODE_READ)
-		ret = seq_lseek(file, offset, origin);
+		ret = seq_lseek(file, offset, whence);
 	else
 		file->f_pos = ret = 1;
 
diff -puN fs/btrfs/file.c~lseek-the-whence-argument-is-called-whence fs/btrfs/file.c
--- a/fs/btrfs/file.c~lseek-the-whence-argument-is-called-whence
+++ a/fs/btrfs/file.c
@@ -2120,7 +2120,7 @@ out:
 	return ret;
 }
 
-static int find_desired_extent(struct inode *inode, loff_t *offset, int origin)
+static int find_desired_extent(struct inode *inode, loff_t *offset, int whence)
 {
 	struct btrfs_root *root = BTRFS_I(inode)->root;
 	struct extent_map *em;
@@ -2154,7 +2154,7 @@ static int find_desired_extent(struct in
 	 * before the position we want in case there is outstanding delalloc
 	 * going on here.
 	 */
-	if (origin == SEEK_HOLE && start != 0) {
+	if (whence == SEEK_HOLE && start != 0) {
 		if (start <= root->sectorsize)
 			em = btrfs_get_extent_fiemap(inode, NULL, 0, 0,
 						     root->sectorsize, 0);
@@ -2188,13 +2188,13 @@ static int find_desired_extent(struct in
 				}
 			}
 
-			if (origin == SEEK_HOLE) {
+			if (whence == SEEK_HOLE) {
 				*offset = start;
 				free_extent_map(em);
 				break;
 			}
 		} else {
-			if (origin == SEEK_DATA) {
+			if (whence == SEEK_DATA) {
 				if (em->block_start == EXTENT_MAP_DELALLOC) {
 					if (start >= inode->i_size) {
 						free_extent_map(em);
@@ -2231,16 +2231,16 @@ out:
 	return ret;
 }
 
-static loff_t btrfs_file_llseek(struct file *file, loff_t offset, int origin)
+static loff_t btrfs_file_llseek(struct file *file, loff_t offset, int whence)
 {
 	struct inode *inode = file->f_mapping->host;
 	int ret;
 
 	mutex_lock(&inode->i_mutex);
-	switch (origin) {
+	switch (whence) {
 	case SEEK_END:
 	case SEEK_CUR:
-		offset = generic_file_llseek(file, offset, origin);
+		offset = generic_file_llseek(file, offset, whence);
 		goto out;
 	case SEEK_DATA:
 	case SEEK_HOLE:
@@ -2249,7 +2249,7 @@ static loff_t btrfs_file_llseek(struct f
 			return -ENXIO;
 		}
 
-		ret = find_desired_extent(inode, &offset, origin);
+		ret = find_desired_extent(inode, &offset, whence);
 		if (ret) {
 			mutex_unlock(&inode->i_mutex);
 			return ret;
diff -puN fs/ceph/dir.c~lseek-the-whence-argument-is-called-whence fs/ceph/dir.c
--- a/fs/ceph/dir.c~lseek-the-whence-argument-is-called-whence
+++ a/fs/ceph/dir.c
@@ -454,7 +454,7 @@ static void reset_readdir(struct ceph_fi
 	fi->flags &= ~CEPH_F_ATEND;
 }
 
-static loff_t ceph_dir_llseek(struct file *file, loff_t offset, int origin)
+static loff_t ceph_dir_llseek(struct file *file, loff_t offset, int whence)
 {
 	struct ceph_file_info *fi = file->private_data;
 	struct inode *inode = file->f_mapping->host;
@@ -463,7 +463,7 @@ static loff_t ceph_dir_llseek(struct fil
 
 	mutex_lock(&inode->i_mutex);
 	retval = -EINVAL;
-	switch (origin) {
+	switch (whence) {
 	case SEEK_END:
 		offset += inode->i_size + 2;   /* FIXME */
 		break;
diff -puN fs/ceph/file.c~lseek-the-whence-argument-is-called-whence fs/ceph/file.c
--- a/fs/ceph/file.c~lseek-the-whence-argument-is-called-whence
+++ a/fs/ceph/file.c
@@ -797,7 +797,7 @@ out:
 /*
  * llseek.  be sure to verify file size on SEEK_END.
  */
-static loff_t ceph_llseek(struct file *file, loff_t offset, int origin)
+static loff_t ceph_llseek(struct file *file, loff_t offset, int whence)
 {
 	struct inode *inode = file->f_mapping->host;
 	int ret;
@@ -805,7 +805,7 @@ static loff_t ceph_llseek(struct file *f
 	mutex_lock(&inode->i_mutex);
 	__ceph_do_pending_vmtruncate(inode);
 
-	if (origin == SEEK_END || origin == SEEK_DATA || origin == SEEK_HOLE) {
+	if (whence == SEEK_END || whence == SEEK_DATA || whence == SEEK_HOLE) {
 		ret = ceph_do_getattr(inode, CEPH_STAT_CAP_SIZE);
 		if (ret < 0) {
 			offset = ret;
@@ -813,7 +813,7 @@ static loff_t ceph_llseek(struct file *f
 		}
 	}
 
-	switch (origin) {
+	switch (whence) {
 	case SEEK_END:
 		offset += inode->i_size;
 		break;
diff -puN fs/cifs/cifsfs.c~lseek-the-whence-argument-is-called-whence fs/cifs/cifsfs.c
--- a/fs/cifs/cifsfs.c~lseek-the-whence-argument-is-called-whence
+++ a/fs/cifs/cifsfs.c
@@ -694,13 +694,13 @@ static ssize_t cifs_file_aio_write(struc
 	return written;
 }
 
-static loff_t cifs_llseek(struct file *file, loff_t offset, int origin)
+static loff_t cifs_llseek(struct file *file, loff_t offset, int whence)
 {
 	/*
-	 * origin == SEEK_END || SEEK_DATA || SEEK_HOLE => we must revalidate
+	 * whence == SEEK_END || SEEK_DATA || SEEK_HOLE => we must revalidate
 	 * the cached file length
 	 */
-	if (origin != SEEK_SET && origin != SEEK_CUR) {
+	if (whence != SEEK_SET && whence != SEEK_CUR) {
 		int rc;
 		struct inode *inode = file->f_path.dentry->d_inode;
 
@@ -727,7 +727,7 @@ static loff_t cifs_llseek(struct file *f
 		if (rc < 0)
 			return (loff_t)rc;
 	}
-	return generic_file_llseek(file, offset, origin);
+	return generic_file_llseek(file, offset, whence);
 }
 
 static int cifs_setlease(struct file *file, long arg, struct file_lock **lease)
diff -puN fs/configfs/dir.c~lseek-the-whence-argument-is-called-whence fs/configfs/dir.c
--- a/fs/configfs/dir.c~lseek-the-whence-argument-is-called-whence
+++ a/fs/configfs/dir.c
@@ -1613,12 +1613,12 @@ static int configfs_readdir(struct file 
 	return 0;
 }
 
-static loff_t configfs_dir_lseek(struct file * file, loff_t offset, int origin)
+static loff_t configfs_dir_lseek(struct file * file, loff_t offset, int whence)
 {
 	struct dentry * dentry = file->f_path.dentry;
 
 	mutex_lock(&dentry->d_inode->i_mutex);
-	switch (origin) {
+	switch (whence) {
 		case 1:
 			offset += file->f_pos;
 		case 0:
diff -puN fs/ext3/dir.c~lseek-the-whence-argument-is-called-whence fs/ext3/dir.c
--- a/fs/ext3/dir.c~lseek-the-whence-argument-is-called-whence
+++ a/fs/ext3/dir.c
@@ -296,17 +296,17 @@ static inline loff_t ext3_get_htree_eof(
  * NOTE: offsets obtained *before* ext3_set_inode_flag(dir, EXT3_INODE_INDEX)
  *       will be invalid once the directory was converted into a dx directory
  */
-loff_t ext3_dir_llseek(struct file *file, loff_t offset, int origin)
+loff_t ext3_dir_llseek(struct file *file, loff_t offset, int whence)
 {
 	struct inode *inode = file->f_mapping->host;
 	int dx_dir = is_dx_dir(inode);
 	loff_t htree_max = ext3_get_htree_eof(file);
 
 	if (likely(dx_dir))
-		return generic_file_llseek_size(file, offset, origin,
+		return generic_file_llseek_size(file, offset, whence,
 					        htree_max, htree_max);
 	else
-		return generic_file_llseek(file, offset, origin);
+		return generic_file_llseek(file, offset, whence);
 }
 
 /*
diff -puN fs/ext4/dir.c~lseek-the-whence-argument-is-called-whence fs/ext4/dir.c
--- a/fs/ext4/dir.c~lseek-the-whence-argument-is-called-whence
+++ a/fs/ext4/dir.c
@@ -334,17 +334,17 @@ static inline loff_t ext4_get_htree_eof(
  *
  * For non-htree, ext4_llseek already chooses the proper max offset.
  */
-loff_t ext4_dir_llseek(struct file *file, loff_t offset, int origin)
+loff_t ext4_dir_llseek(struct file *file, loff_t offset, int whence)
 {
 	struct inode *inode = file->f_mapping->host;
 	int dx_dir = is_dx_dir(inode);
 	loff_t htree_max = ext4_get_htree_eof(file);
 
 	if (likely(dx_dir))
-		return generic_file_llseek_size(file, offset, origin,
+		return generic_file_llseek_size(file, offset, whence,
 						    htree_max, htree_max);
 	else
-		return ext4_llseek(file, offset, origin);
+		return ext4_llseek(file, offset, whence);
 }
 
 /*
diff -puN fs/ext4/file.c~lseek-the-whence-argument-is-called-whence fs/ext4/file.c
--- a/fs/ext4/file.c~lseek-the-whence-argument-is-called-whence
+++ a/fs/ext4/file.c
@@ -303,7 +303,7 @@ static int ext4_file_open(struct inode *
  * page cache has data or not.
  */
 static int ext4_find_unwritten_pgoff(struct inode *inode,
-				     int origin,
+				     int whence,
 				     struct ext4_map_blocks *map,
 				     loff_t *offset)
 {
@@ -333,10 +333,10 @@ static int ext4_find_unwritten_pgoff(str
 		nr_pages = pagevec_lookup(&pvec, inode->i_mapping, index,
 					  (pgoff_t)num);
 		if (nr_pages == 0) {
-			if (origin == SEEK_DATA)
+			if (whence == SEEK_DATA)
 				break;
 
-			BUG_ON(origin != SEEK_HOLE);
+			BUG_ON(whence != SEEK_HOLE);
 			/*
 			 * If this is the first time to go into the loop and
 			 * offset is not beyond the end offset, it will be a
@@ -352,7 +352,7 @@ static int ext4_find_unwritten_pgoff(str
 		 * offset is smaller than the first page offset, it will be a
 		 * hole at this offset.
 		 */
-		if (lastoff == startoff && origin == SEEK_HOLE &&
+		if (lastoff == startoff && whence == SEEK_HOLE &&
 		    lastoff < page_offset(pvec.pages[0])) {
 			found = 1;
 			break;
@@ -366,7 +366,7 @@ static int ext4_find_unwritten_pgoff(str
 			 * If the current offset is not beyond the end of given
 			 * range, it will be a hole.
 			 */
-			if (lastoff < endoff && origin == SEEK_HOLE &&
+			if (lastoff < endoff && whence == SEEK_HOLE &&
 			    page->index > end) {
 				found = 1;
 				*offset = lastoff;
@@ -391,10 +391,10 @@ static int ext4_find_unwritten_pgoff(str
 				do {
 					if (buffer_uptodate(bh) ||
 					    buffer_unwritten(bh)) {
-						if (origin == SEEK_DATA)
+						if (whence == SEEK_DATA)
 							found = 1;
 					} else {
-						if (origin == SEEK_HOLE)
+						if (whence == SEEK_HOLE)
 							found = 1;
 					}
 					if (found) {
@@ -416,7 +416,7 @@ static int ext4_find_unwritten_pgoff(str
 		 * The no. of pages is less than our desired, that would be a
 		 * hole in there.
 		 */
-		if (nr_pages < num && origin == SEEK_HOLE) {
+		if (nr_pages < num && whence == SEEK_HOLE) {
 			found = 1;
 			*offset = lastoff;
 			break;
@@ -609,7 +609,7 @@ static loff_t ext4_seek_hole(struct file
  * by calling generic_file_llseek_size() with the appropriate maxbytes
  * value for each.
  */
-loff_t ext4_llseek(struct file *file, loff_t offset, int origin)
+loff_t ext4_llseek(struct file *file, loff_t offset, int whence)
 {
 	struct inode *inode = file->f_mapping->host;
 	loff_t maxbytes;
@@ -619,11 +619,11 @@ loff_t ext4_llseek(struct file *file, lo
 	else
 		maxbytes = inode->i_sb->s_maxbytes;
 
-	switch (origin) {
+	switch (whence) {
 	case SEEK_SET:
 	case SEEK_CUR:
 	case SEEK_END:
-		return generic_file_llseek_size(file, offset, origin,
+		return generic_file_llseek_size(file, offset, whence,
 						maxbytes, i_size_read(inode));
 	case SEEK_DATA:
 		return ext4_seek_data(file, offset, maxbytes);
diff -puN fs/fuse/file.c~lseek-the-whence-argument-is-called-whence fs/fuse/file.c
--- a/fs/fuse/file.c~lseek-the-whence-argument-is-called-whence
+++ a/fs/fuse/file.c
@@ -1699,19 +1699,19 @@ static sector_t fuse_bmap(struct address
 	return err ? 0 : outarg.block;
 }
 
-static loff_t fuse_file_llseek(struct file *file, loff_t offset, int origin)
+static loff_t fuse_file_llseek(struct file *file, loff_t offset, int whence)
 {
 	loff_t retval;
 	struct inode *inode = file->f_path.dentry->d_inode;
 
 	/* No i_mutex protection necessary for SEEK_CUR and SEEK_SET */
-	if (origin == SEEK_CUR || origin == SEEK_SET)
-		return generic_file_llseek(file, offset, origin);
+	if (whence == SEEK_CUR || whence == SEEK_SET)
+		return generic_file_llseek(file, offset, whence);
 
 	mutex_lock(&inode->i_mutex);
 	retval = fuse_update_attributes(inode, NULL, file, NULL);
 	if (!retval)
-		retval = generic_file_llseek(file, offset, origin);
+		retval = generic_file_llseek(file, offset, whence);
 	mutex_unlock(&inode->i_mutex);
 
 	return retval;
diff -puN fs/gfs2/file.c~lseek-the-whence-argument-is-called-whence fs/gfs2/file.c
--- a/fs/gfs2/file.c~lseek-the-whence-argument-is-called-whence
+++ a/fs/gfs2/file.c
@@ -44,7 +44,7 @@
  * gfs2_llseek - seek to a location in a file
  * @file: the file
  * @offset: the offset
- * @origin: Where to seek from (SEEK_SET, SEEK_CUR, or SEEK_END)
+ * @whence: Where to seek from (SEEK_SET, SEEK_CUR, or SEEK_END)
  *
  * SEEK_END requires the glock for the file because it references the
  * file's size.
@@ -52,26 +52,26 @@
  * Returns: The new offset, or errno
  */
 
-static loff_t gfs2_llseek(struct file *file, loff_t offset, int origin)
+static loff_t gfs2_llseek(struct file *file, loff_t offset, int whence)
 {
 	struct gfs2_inode *ip = GFS2_I(file->f_mapping->host);
 	struct gfs2_holder i_gh;
 	loff_t error;
 
-	switch (origin) {
+	switch (whence) {
 	case SEEK_END: /* These reference inode->i_size */
 	case SEEK_DATA:
 	case SEEK_HOLE:
 		error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY,
 					   &i_gh);
 		if (!error) {
-			error = generic_file_llseek(file, offset, origin);
+			error = generic_file_llseek(file, offset, whence);
 			gfs2_glock_dq_uninit(&i_gh);
 		}
 		break;
 	case SEEK_CUR:
 	case SEEK_SET:
-		error = generic_file_llseek(file, offset, origin);
+		error = generic_file_llseek(file, offset, whence);
 		break;
 	default:
 		error = -EINVAL;
diff -puN fs/nfs/dir.c~lseek-the-whence-argument-is-called-whence fs/nfs/dir.c
--- a/fs/nfs/dir.c~lseek-the-whence-argument-is-called-whence
+++ a/fs/nfs/dir.c
@@ -870,7 +870,7 @@ out:
 	return res;
 }
 
-static loff_t nfs_llseek_dir(struct file *filp, loff_t offset, int origin)
+static loff_t nfs_llseek_dir(struct file *filp, loff_t offset, int whence)
 {
 	struct dentry *dentry = filp->f_path.dentry;
 	struct inode *inode = dentry->d_inode;
@@ -879,10 +879,10 @@ static loff_t nfs_llseek_dir(struct file
 	dfprintk(FILE, "NFS: llseek dir(%s/%s, %lld, %d)\n",
 			dentry->d_parent->d_name.name,
 			dentry->d_name.name,
-			offset, origin);
+			offset, whence);
 
 	mutex_lock(&inode->i_mutex);
-	switch (origin) {
+	switch (whence) {
 		case 1:
 			offset += filp->f_pos;
 		case 0:
diff -puN fs/nfs/file.c~lseek-the-whence-argument-is-called-whence fs/nfs/file.c
--- a/fs/nfs/file.c~lseek-the-whence-argument-is-called-whence
+++ a/fs/nfs/file.c
@@ -119,18 +119,18 @@ force_reval:
 	return __nfs_revalidate_inode(server, inode);
 }
 
-loff_t nfs_file_llseek(struct file *filp, loff_t offset, int origin)
+loff_t nfs_file_llseek(struct file *filp, loff_t offset, int whence)
 {
 	dprintk("NFS: llseek file(%s/%s, %lld, %d)\n",
 			filp->f_path.dentry->d_parent->d_name.name,
 			filp->f_path.dentry->d_name.name,
-			offset, origin);
+			offset, whence);
 
 	/*
-	 * origin == SEEK_END || SEEK_DATA || SEEK_HOLE => we must revalidate
+	 * whence == SEEK_END || SEEK_DATA || SEEK_HOLE => we must revalidate
 	 * the cached file length
 	 */
-	if (origin != SEEK_SET && origin != SEEK_CUR) {
+	if (whence != SEEK_SET && whence != SEEK_CUR) {
 		struct inode *inode = filp->f_mapping->host;
 
 		int retval = nfs_revalidate_file_size(inode, filp);
@@ -138,7 +138,7 @@ loff_t nfs_file_llseek(struct file *filp
 			return (loff_t)retval;
 	}
 
-	return generic_file_llseek(filp, offset, origin);
+	return generic_file_llseek(filp, offset, whence);
 }
 EXPORT_SYMBOL_GPL(nfs_file_llseek);
 
diff -puN fs/ocfs2/extent_map.c~lseek-the-whence-argument-is-called-whence fs/ocfs2/extent_map.c
--- a/fs/ocfs2/extent_map.c~lseek-the-whence-argument-is-called-whence
+++ a/fs/ocfs2/extent_map.c
@@ -832,7 +832,7 @@ out:
 	return ret;
 }
 
-int ocfs2_seek_data_hole_offset(struct file *file, loff_t *offset, int origin)
+int ocfs2_seek_data_hole_offset(struct file *file, loff_t *offset, int whence)
 {
 	struct inode *inode = file->f_mapping->host;
 	int ret;
@@ -843,7 +843,7 @@ int ocfs2_seek_data_hole_offset(struct f
 	struct buffer_head *di_bh = NULL;
 	struct ocfs2_extent_rec rec;
 
-	BUG_ON(origin != SEEK_DATA && origin != SEEK_HOLE);
+	BUG_ON(whence != SEEK_DATA && whence != SEEK_HOLE);
 
 	ret = ocfs2_inode_lock(inode, &di_bh, 0);
 	if (ret) {
@@ -859,7 +859,7 @@ int ocfs2_seek_data_hole_offset(struct f
 	}
 
 	if (OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL) {
-		if (origin == SEEK_HOLE)
+		if (whence == SEEK_HOLE)
 			*offset = inode->i_size;
 		goto out_unlock;
 	}
@@ -888,8 +888,8 @@ int ocfs2_seek_data_hole_offset(struct f
 			is_data = (rec.e_flags & OCFS2_EXT_UNWRITTEN) ?  0 : 1;
 		}
 
-		if ((!is_data && origin == SEEK_HOLE) ||
-		    (is_data && origin == SEEK_DATA)) {
+		if ((!is_data && whence == SEEK_HOLE) ||
+		    (is_data && whence == SEEK_DATA)) {
 			if (extoff > *offset)
 				*offset = extoff;
 			goto out_unlock;
@@ -899,7 +899,7 @@ int ocfs2_seek_data_hole_offset(struct f
 			cpos += clen;
 	}
 
-	if (origin == SEEK_HOLE) {
+	if (whence == SEEK_HOLE) {
 		extoff = cpos;
 		extoff <<= cs_bits;
 		extlen = clen;
diff -puN fs/ocfs2/file.c~lseek-the-whence-argument-is-called-whence fs/ocfs2/file.c
--- a/fs/ocfs2/file.c~lseek-the-whence-argument-is-called-whence
+++ a/fs/ocfs2/file.c
@@ -2637,14 +2637,14 @@ bail:
 }
 
 /* Refer generic_file_llseek_unlocked() */
-static loff_t ocfs2_file_llseek(struct file *file, loff_t offset, int origin)
+static loff_t ocfs2_file_llseek(struct file *file, loff_t offset, int whence)
 {
 	struct inode *inode = file->f_mapping->host;
 	int ret = 0;
 
 	mutex_lock(&inode->i_mutex);
 
-	switch (origin) {
+	switch (whence) {
 	case SEEK_SET:
 		break;
 	case SEEK_END:
@@ -2659,7 +2659,7 @@ static loff_t ocfs2_file_llseek(struct f
 		break;
 	case SEEK_DATA:
 	case SEEK_HOLE:
-		ret = ocfs2_seek_data_hole_offset(file, &offset, origin);
+		ret = ocfs2_seek_data_hole_offset(file, &offset, whence);
 		if (ret)
 			goto out;
 		break;
diff -puN fs/pstore/inode.c~lseek-the-whence-argument-is-called-whence fs/pstore/inode.c
--- a/fs/pstore/inode.c~lseek-the-whence-argument-is-called-whence
+++ a/fs/pstore/inode.c
@@ -151,13 +151,13 @@ static int pstore_file_open(struct inode
 	return 0;
 }
 
-static loff_t pstore_file_llseek(struct file *file, loff_t off, int origin)
+static loff_t pstore_file_llseek(struct file *file, loff_t off, int whence)
 {
 	struct seq_file *sf = file->private_data;
 
 	if (sf->op)
-		return seq_lseek(file, off, origin);
-	return default_llseek(file, off, origin);
+		return seq_lseek(file, off, whence);
+	return default_llseek(file, off, whence);
 }
 
 static const struct file_operations pstore_file_operations = {
diff -puN fs/ubifs/dir.c~lseek-the-whence-argument-is-called-whence fs/ubifs/dir.c
--- a/fs/ubifs/dir.c~lseek-the-whence-argument-is-called-whence
+++ a/fs/ubifs/dir.c
@@ -453,11 +453,11 @@ out:
 }
 
 /* If a directory is seeked, we have to free saved readdir() state */
-static loff_t ubifs_dir_llseek(struct file *file, loff_t offset, int origin)
+static loff_t ubifs_dir_llseek(struct file *file, loff_t offset, int whence)
 {
 	kfree(file->private_data);
 	file->private_data = NULL;
-	return generic_file_llseek(file, offset, origin);
+	return generic_file_llseek(file, offset, whence);
 }
 
 /* Free saved readdir() state when the directory is closed */
_

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Re: [PATCH] tmpfs: support SEEK_DATA and SEEK_HOLE (reprise)

[Hugh Dickins]

On Thu, 29 Nov 2012, Andrew Morton wrote:
> On Wed, 28 Nov 2012 17:22:03 -0800 (PST)
> Hugh Dickins <hughd@google.com> wrote:
> 
> > +/*
> > + * llseek SEEK_DATA or SEEK_HOLE through the radix_tree.
> > + */
> > +static pgoff_t shmem_seek_hole_data(struct address_space *mapping,
> > +				    pgoff_t index, pgoff_t end, int origin)
> 
> So I was starting at this wondering what on earth "origin" is and why
> it has the fishy-in-this-context type "int".
> 
> There is a pretty well established convention that the lseek seek mode
> is called "whence".
> 
> The below gets most of it.  Too anal?

No, not too anal: I'm all in favour of "whence", which is indeed
the name of that lseek argument - since mediaeval times I believe.

It's good to have words like that in the kernel source: while you're
in the mood, please see if you can find good homes for "whither" and
"thrice" and "widdershins".

Thanks!
Hugh

> 
> 
> From: Andrew Morton <akpm@linux-foundation.org>
> Subject: lseek: the "whence" argument is called "whence"
> 
> But the kernel decided to call it "origin" instead.  Fix most of the
> sites.
> 
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> ---
> 
>  fs/bad_inode.c           |    2 -
>  fs/block_dev.c           |    4 +--
>  fs/btrfs/file.c          |   16 +++++++-------
>  fs/ceph/dir.c            |    4 +--
>  fs/ceph/file.c           |    6 ++---
>  fs/cifs/cifsfs.c         |    8 +++----
>  fs/configfs/dir.c        |    4 +--
>  fs/ext3/dir.c            |    6 ++---
>  fs/ext4/dir.c            |    6 ++---
>  fs/ext4/file.c           |   22 ++++++++++----------
>  fs/fuse/file.c           |    8 +++----
>  fs/gfs2/file.c           |   10 ++++-----
>  fs/libfs.c               |    4 +--
>  fs/nfs/dir.c             |    6 ++---
>  fs/nfs/file.c            |   10 ++++-----
>  fs/ocfs2/extent_map.c    |   12 +++++------
>  fs/ocfs2/file.c          |    6 ++---
>  fs/pstore/inode.c        |    6 ++---
>  fs/read_write.c          |   40 ++++++++++++++++++-------------------
>  fs/seq_file.c            |    4 +--
>  fs/ubifs/dir.c           |    4 +--
>  include/linux/fs.h       |   12 +++++------
>  include/linux/ftrace.h   |    4 +--
>  include/linux/syscalls.h |    4 +--
>  kernel/trace/ftrace.c    |    4 +--
>  mm/shmem.c               |   20 +++++++++---------
>  26 files changed, 116 insertions(+), 116 deletions(-)

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Re: [PATCH] tmpfs: support SEEK_DATA and SEEK_HOLE (reprise)

[Andrew Morton]

On Thu, 29 Nov 2012 15:29:15 -0800 (PST)
Hugh Dickins <hughd@google.com> wrote:

> On Thu, 29 Nov 2012, Andrew Morton wrote:
> > On Wed, 28 Nov 2012 17:22:03 -0800 (PST)
> > Hugh Dickins <hughd@google.com> wrote:
> > 
> > > +/*
> > > + * llseek SEEK_DATA or SEEK_HOLE through the radix_tree.
> > > + */
> > > +static pgoff_t shmem_seek_hole_data(struct address_space *mapping,
> > > +				    pgoff_t index, pgoff_t end, int origin)
> > 
> > So I was starting at this wondering what on earth "origin" is and why
> > it has the fishy-in-this-context type "int".
> > 
> > There is a pretty well established convention that the lseek seek mode
> > is called "whence".
> > 
> > The below gets most of it.  Too anal?
> 
> No, not too anal: I'm all in favour of "whence", which is indeed
> the name of that lseek argument - since mediaeval times I believe.

Alas, the rest of us don't have personal memories from those days.

> It's good to have words like that in the kernel source: while you're
> in the mood, please see if you can find good homes for "whither" and
> "thrice" and "widdershins".

We use "thrice" quite a lot.  And "whither" once coz alfa peeps cnat spel. 
No widdershins yet.

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