Re: [PATCH 1/7] BTRFS: Fix lseek return value for error

On Thu, Sep 15, 2011 at 04:06:47PM -0700, Andi Kleen wrote:

From: Andi Kleen <redacted>

Introduced by 9a4327ca1f45f82edad7dc0a4e52ce9316e0950c

I think this should go to Chris/Linus ASAP.  But a slightly better
patch description wouldn't hurt either.

Also any reason you captialize BTRFS?

---end quoted text---

On Fri, Sep 16, 2011 at 11:48:15AM -0400, Christoph Hellwig wrote:

On Thu, Sep 15, 2011 at 04:06:47PM -0700, Andi Kleen wrote:

quoted

From: Andi Kleen <redacted>

Introduced by 9a4327ca1f45f82edad7dc0a4e52ce9316e0950c

I think this should go to Chris/Linus ASAP.  But a slightly better
patch description wouldn't hurt either.

Josef acked it earlier, but with a missing Chris the btrfs merge
pipeline seems to be disfunctional at the moment.

-Andi

I once posted a similar patch for this issue which can be found at:
http://www.spinics.net/lists/linux-btrfs/msg12169.html

with an additional improvement if the offset is larger or equal to the
file size, return -ENXIO in directly:

if (offset >= inode->i_size) {
                        mutex_unlock(&inode->i_mutex);
                        return -ENXIO;
                }


Thanks,
-Jeff
On 09/16/2011 11:48 PM, Christoph Hellwig wrote:

On Thu, Sep 15, 2011 at 04:06:47PM -0700, Andi Kleen wrote:

quoted

From: Andi Kleen <redacted>

Introduced by 9a4327ca1f45f82edad7dc0a4e52ce9316e0950c

I think this should go to Chris/Linus ASAP.  But a slightly better
patch description wouldn't hurt either.

Also any reason you captialize BTRFS?

quoted

Signed-off-by: Andi Kleen <redacted>
---
 fs/btrfs/file.c |   13 +++++++------
 1 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 3c3abff..7ec0a24 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c

@@ -1818,19 +1818,17 @@ static loff_t btrfs_file_llseek(struct file *file, loff_t offset, int origin)
 	case SEEK_DATA:
 	case SEEK_HOLE:
 		ret = find_desired_extent(inode, &offset, origin);
-		if (ret) {
-			mutex_unlock(&inode->i_mutex);
-			return ret;
-		}
+		if (ret)
+			goto error;
 	}
 
 	if (offset < 0 && !(file->f_mode & FMODE_UNSIGNED_OFFSET)) {
 		ret = -EINVAL;
-		goto out;
+		goto error;
 	}
 	if (offset > inode->i_sb->s_maxbytes) {
 		ret = -EINVAL;
-		goto out;
+		goto error;
 	}
 
 	/* Special lock needed here? */

@@ -1841,6 +1839,9 @@ static loff_t btrfs_file_llseek(struct file *file, loff_t offset, int origin)
 out:
 	mutex_unlock(&inode->i_mutex);
 	return offset;
+error:
+	mutex_unlock(&inode->i_mutex);
+	return ret;
 }
 
 const struct file_operations btrfs_file_operations = {

-- 
1.7.4.4

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On 2011-09-17, at 12:10 AM, Jeff Liu [off-list ref] wrote:

I once posted a similar patch for this issue which can be found at:
http://www.spinics.net/lists/linux-btrfs/msg12169.html

with an additional improvement if the offset is larger or equal to the
file size, return -ENXIO in directly:

               if (offset >= inode->i_size) {
                       mutex_unlock(&inode->i_mutex);
                       return -ENXIO;
               }

Except that is wrong, because it would then be impossible to write sparse files. 

Thanks,
-Jeff
On 09/16/2011 11:48 PM, Christoph Hellwig wrote:

quoted

On Thu, Sep 15, 2011 at 04:06:47PM -0700, Andi Kleen wrote:

quoted

From: Andi Kleen <redacted>

Introduced by 9a4327ca1f45f82edad7dc0a4e52ce9316e0950c

I think this should go to Chris/Linus ASAP.  But a slightly better
patch description wouldn't hurt either.

Also any reason you captialize BTRFS?

quoted

Signed-off-by: Andi Kleen <redacted>
---
fs/btrfs/file.c |   13 +++++++------
1 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 3c3abff..7ec0a24 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c

@@ -1818,19 +1818,17 @@ static loff_t btrfs_file_llseek(struct file *file, loff_t offset, int origin)
   case SEEK_DATA:
   case SEEK_HOLE:
       ret = find_desired_extent(inode, &offset, origin);
-        if (ret) {
-            mutex_unlock(&inode->i_mutex);
-            return ret;
-        }
+        if (ret)
+            goto error;
   }

   if (offset < 0 && !(file->f_mode & FMODE_UNSIGNED_OFFSET)) {
       ret = -EINVAL;
-        goto out;
+        goto error;
   }
   if (offset > inode->i_sb->s_maxbytes) {
       ret = -EINVAL;
-        goto out;
+        goto error;
   }

   /* Special lock needed here? */

@@ -1841,6 +1839,9 @@ static loff_t btrfs_file_llseek(struct file *file, loff_t offset, int origin)

out:
   mutex_unlock(&inode->i_mutex);
   return offset;
+error:
+    mutex_unlock(&inode->i_mutex);
+    return ret;
}

const struct file_operations btrfs_file_operations = {
-- 
1.7.4.4

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quoted

with an additional improvement if the offset is larger or equal to the
file size, return -ENXIO in directly:

               if (offset >= inode->i_size) {
                       mutex_unlock(&inode->i_mutex);
                       return -ENXIO;
               }

Except that is wrong, because it would then be impossible to write sparse files. 

And also i_size must be always read with i_size_read()

Anyways clearly there's a problem in btrfs land with merging fixes in time.
Is anyone collecting patches while Chris is gone?

-Andi

Hi Andreas and Andi,

Thanks for your comments.

On 09/18/2011 09:46 AM, Andi Kleen wrote:

quoted

quoted

with an additional improvement if the offset is larger or equal to the
file size, return -ENXIO in directly:

               if (offset >= inode->i_size) {
                       mutex_unlock(&inode->i_mutex);
                       return -ENXIO;
               }

Except that is wrong, because it would then be impossible to write sparse files. 

Per my tryout, except that, if the offset >= source file size, call
lseek(fd, offset, SEEK_DATA/SEEK_HOLE) against Btrfs will always return
the total file size rather than -ENXIO.  however, our desired result it
-ENXIO in this case, Am I right?

And also i_size must be always read with i_size_read()

Thanks for pointing this out!
Would you please kindly review the revised as below?

Signed-off-by: Jie Liu <redacted>

---
 fs/btrfs/file.c |    9 +++++++--
 1 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index e7872e4..40c1ef3 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c

@@ -1813,6 +1813,11 @@ static loff_t btrfs_file_llseek(struct file

*file, loff_t offset, int origin)
 		goto out;
 	case SEEK_DATA:
 	case SEEK_HOLE:
+		if (offset >= i_size_read(inode)) {
+			mutex_unlock(&inode->i_mutex);
+			return -ENXIO;
+		}
+
 		ret = find_desired_extent(inode, &offset, origin);
 		if (ret) {
 			mutex_unlock(&inode->i_mutex);

@@ -1821,11 +1826,11 @@ static loff_t btrfs_file_llseek(struct file

*file, loff_t offset, int origin)
 	}

 	if (offset < 0 && !(file->f_mode & FMODE_UNSIGNED_OFFSET)) {
-		ret = -EINVAL;
+		offset = -EINVAL;
 		goto out;
 	}
 	if (offset > inode->i_sb->s_maxbytes) {
-		ret = -EINVAL;
+		offset = -EINVAL;
 		goto out;
 	}

-- 
1.7.4.1

Il 18/09/2011 09:29, Jeff Liu ha scritto:

Hi Andreas and Andi,

Thanks for your comments.

On 09/18/2011 09:46 AM, Andi Kleen wrote:

quoted

quoted

quoted

with an additional improvement if the offset is larger or equal to the
file size, return -ENXIO in directly:

                if (offset>= inode->i_size) {
                        mutex_unlock(&inode->i_mutex);
                        return -ENXIO;
                }

Except that is wrong, because it would then be impossible to write sparse files.

Per my tryout, except that, if the offset>= source file size, call
lseek(fd, offset, SEEK_DATA/SEEK_HOLE) against Btrfs will always return
the total file size rather than -ENXIO.  however, our desired result it
-ENXIO in this case, Am I right?

Yes, ENXIO should be the operation result.

=D4=DA 2011-9-18=A3=AC=CF=C2=CE=E74:42=A3=AC Marco Stornelli =D0=B4=B5=C0=
=A3=BA

Il 18/09/2011 09:29, Jeff Liu ha scritto:

quoted

Hi Andreas and Andi,
=20
Thanks for your comments.
=20
On 09/18/2011 09:46 AM, Andi Kleen wrote:
=20

quoted

quoted

quoted

with an additional improvement if the offset is larger or equal t=

o the

quoted

quoted

quoted

quoted

file size, return -ENXIO in directly:
=20
               if (offset>=3D inode->i_size) {
                       mutex_unlock(&inode->i_mutex);
                       return -ENXIO;
               }

=20
Except that is wrong, because it would then be impossible to write=

 sparse files.

quoted

=20
Per my tryout, except that, if the offset>=3D source file size, call
lseek(fd, offset, SEEK_DATA/SEEK_HOLE) against Btrfs will always ret=

urn

quoted

the total file size rather than -ENXIO.  however, our desired result=

 it

quoted

-ENXIO in this case, Am I right?
=20

=20
Yes, ENXIO should be the operation result.

Thanks for your kind confirmation.


-Jeff

Excerpts from Jeff liu's message of 2011-09-18 06:33:38 -0400:

=20
=E5=9C=A8 2011-9-18=EF=BC=8C=E4=B8=8B=E5=8D=884:42=EF=BC=8C Marco Sto=

rnelli =E5=86=99=E9=81=93=EF=BC=9A

=20

quoted

Il 18/09/2011 09:29, Jeff Liu ha scritto:

quoted

Hi Andreas and Andi,
=20
Thanks for your comments.
=20
On 09/18/2011 09:46 AM, Andi Kleen wrote:
=20

quoted

quoted

quoted

with an additional improvement if the offset is larger or equal=

 to the

quoted

quoted

quoted

quoted

quoted

file size, return -ENXIO in directly:
=20
               if (offset>=3D inode->i_size) {
                       mutex_unlock(&inode->i_mutex);
                       return -ENXIO;
               }

=20
Except that is wrong, because it would then be impossible to wri=

te sparse files.

quoted

quoted

=20
Per my tryout, except that, if the offset>=3D source file size, ca=

ll

quoted

quoted

lseek(fd, offset, SEEK_DATA/SEEK_HOLE) against Btrfs will always r=

eturn

quoted

quoted

the total file size rather than -ENXIO.  however, our desired resu=

lt it

quoted

quoted

-ENXIO in this case, Am I right?
=20

=20
Yes, ENXIO should be the operation result.

=20
Thanks for your kind confirmation.

Thanks everyone, I've put Jeff's last version of this in my queue.

-chris

Thanks everyone, I've put Jeff's last version of this in my queue.

Can you post the version you merged? The previous ones all had issues.

-Andi

Excerpts from Andi Kleen's message of 2011-09-19 13:52:03 -0400:

quoted

Thanks everyone, I've put Jeff's last version of this in my queue.

Can you post the version you merged? The previous ones all had issues.

https://github.com/chrismason/linux/commit/48802c8ae2a9d618ec734a61283d645ad527e06c

This was the last one sent, I thought it combined all the fixes.


commit 48802c8ae2a9d618ec734a61283d645ad527e06c
Author: Jeff Liu [off-list ref]
Date:   Sun Sep 18 10:34:02 2011 -0400

    BTRFS: Fix lseek return value for error
    
    The recent reworking of btrfs' lseek lead to incorrect
    values being returned.  This adds checks for seeking
    beyond EOF in SEEK_HOLE and makes sure the error
    values come back correct.
    
    Andi Kleen also sent in similar patches.
    
    Signed-off-by: Jie Liu [off-list ref]
    Reported-by: Andi Kleen [off-list ref]
    Signed-off-by: Chris Mason [off-list ref]

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 3c3abff..a381cd2 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c

@@ -1817,6 +1817,11 @@ static loff_t btrfs_file_llseek(struct file *file, loff_t offset, int origin)
 		goto out;
 	case SEEK_DATA:
 	case SEEK_HOLE:
+		if (offset >= i_size_read(inode)) {
+			mutex_unlock(&inode->i_mutex);
+			return -ENXIO;
+		}
+
 		ret = find_desired_extent(inode, &offset, origin);
 		if (ret) {
 			mutex_unlock(&inode->i_mutex);

@@ -1825,11 +1830,11 @@ static loff_t btrfs_file_llseek(struct file *file, loff_t offset, int origin)
 	}
 
 	if (offset < 0 && !(file->f_mode & FMODE_UNSIGNED_OFFSET)) {
-		ret = -EINVAL;
+		offset = -EINVAL;
 		goto out;
 	}
 	if (offset > inode->i_sb->s_maxbytes) {
-		ret = -EINVAL;
+		offset = -EINVAL;
 		goto out;
 	}
 

On Mon, Sep 19, 2011 at 03:30:02PM -0400, Chris Mason wrote:

Excerpts from Andi Kleen's message of 2011-09-19 13:52:03 -0400:

quoted

quoted

Thanks everyone, I've put Jeff's last version of this in my queue.

Can you post the version you merged? The previous ones all had issues.

https://github.com/chrismason/linux/commit/48802c8ae2a9d618ec734a61283d645ad527e06c

This was the last one sent, I thought it combined all the fixes.

Ok looks good, but it will be all obsolete once my patchkit lseek
get in (except for the SEEK_DATA/HOLE hunk)

-Andi

Excerpts from Andi Kleen's message of 2011-09-19 15:59:52 -0400:

On Mon, Sep 19, 2011 at 03:30:02PM -0400, Chris Mason wrote:

quoted

Excerpts from Andi Kleen's message of 2011-09-19 13:52:03 -0400:

quoted

quoted

Thanks everyone, I've put Jeff's last version of this in my queue.

Can you post the version you merged? The previous ones all had issues.

https://github.com/chrismason/linux/commit/48802c8ae2a9d618ec734a61283d645ad527e06c

This was the last one sent, I thought it combined all the fixes.

Ok looks good, but it will be all obsolete once my patchkit lseek
get in (except for the SEEK_DATA/HOLE hunk)

Yeah, it's similar to yours except for the hole hunk.  Your gotos are
fine by me, whatever makes your patch cleaner.

-chris