Greetings,
I've stumbled across a 2.6.22->2.6.23 regression.  First md5sum access

of an empty NTFS file leads to kernel I/O error gripe, a second access

leaves md5sum hung.  2.6.22.10 has no trouble accessing this file.
Looking at the 22->23 diff, I don't see a quick and dirty stab

candidate, and since I'm preparing for a 5 week separation from my box

<twitch>, I doubt I'll have time to do a bisect.  /me punts.
root@Homer: md5sum '/windows/C/Dokumente und Einstellungen/All Users/Anwendungsdaten/Microsoft/Network/Connections/Pbk/rasphone.pbk'

md5sum: /windows/C/Dokumente und Einstellungen/All Users/Anwendungsdaten/Microsoft/Network/Connections/Pbk/rasphone.pbk: Input/output error
[  228.551859] NTFS-fs error (device hda1): ntfs_read_compressed_block(): ntfs_map_runlist() failed. Cannot read compression block.
[  401.721890] md5sum        D eee53d64     0  7249   7019

[  401.727155]        eee53d78 00200082 00000002 eee53d64 eee53d5c 00000000 e9b006b0 e9b00700

[  401.735469]        5f6b3463 c0677060 c067a080 e9b00860 c180d080 00000000 c180d080 c180d108

[  401.743991]        00000001 00200086 e9b006e0 00200086 f79ca640 eee53d94 0000b4d3 00200202

[  401.752514] Call Trace:

[  401.755155]  [<c04b57bf>] io_schedule+0x1e/0x28

[  401.759711]  [<c015a269>] sync_page+0x34/0x3f

[  401.764102]  [<c04b5b78>] __wait_on_bit_lock+0x40/0x63

[  401.769281]  [<c015a221>] __lock_page+0x54/0x5c

[  401.773845]  [<c015a826>] do_generic_mapping_read+0x236/0x4e7

[  401.779629]  [<c015c165>] generic_file_aio_read+0xff/0x198

[  401.785138]  [<c017851c>] do_sync_read+0xd0/0x106

[  401.789873]  [<c0178cff>] vfs_read+0x89/0x11d

[  401.794266]  [<c0179164>] sys_read+0x3d/0x64

[  401.798569]  [<c01041ba>] syscall_call+0x7/0xb

[  401.803039]  =======================
-

Hi,
Could you post the complete dmesg output, please?
Nothing related has changed in the NTFS driver between 2.6.22.10 and

2.6.23 so I expect something else to be at fault here.
Could you post your .config as well, please?
Best regards,
	Anton

--

Anton Altaparmakov <aia21 at cam.ac.uk> (replace at with @)

Unix Support, Computing Service, University of Cambridge, CB2 3QH, UK

Linux NTFS maintainer, http://www.linux-ntfs.org/
-

Attached.  This is after a reboot though, but a fresh attempt to sum the
Also attached.
-Mike

Hi Mike,
Thanks for the files.  That is really odd.  And you are sure this just

works with 2.6.22.10 on the exact same file?  Have you run  "chkdsk /

f /v /x" on the NTFS volume from Windows?
Would you be able to apply the attached patch to your 2.6.23.1 kernel

and try again and then send me the NTFS error messages?  The patch

should cause more verbose error reporting to happen...  Thanks!
Best regards,
	Anton
--

Anton Altaparmakov <aia21 at cam.ac.uk> (replace at with @)

Unix Support, Computing Service, University of Cambridge, CB2 3QH, UK

Linux NTFS maintainer, http://www.linux-ntfs.org/
-

Yes, 2.6.22.10 can md5sum that file just fine, did it several times.  I
[  249.009250] NTFS-fs error (device hda1): ntfs_map_runlist_nolock(): vcn 0x0 >= end_vcn 0x0 for inode 0x490f, error 0.

[  249.020142] NTFS-fs error (device hda1): ntfs_read_compressed_block(): ntfs_map_runlist() failed. Cannot read compression block.
	-Mike
-

I now have fun chkdsk, it didn't gripe, and the error is still present.
	-Mike
-

Not being very good at walking away from unsolved mysteries, I chased it

down.  The problem is that...

	commit[a32ea1e1f925399e0d81ca3f7394a44a6dafa12c] Fix read/truncate race

...calls ntfs_readpage() for a zero i_size inode, which it isn't

accustomed to.
Below is the hammer which made my box a happy camper again.
diff --git a/fs/ntfs/aops.c b/fs/ntfs/aops.c

index 6e5c253..ddab5a3 100644

--- a/fs/ntfs/aops.c

+++ b/fs/ntfs/aops.c

@@ -401,7 +401,7 @@ static int ntfs_readpage(struct file *file, struct page *page)

 	MFT_RECORD *mrec;

 	unsigned long flags;

 	u32 attr_len;

-	int err = 0;

+	int err = 0, once = 0;
 retry_readpage:

 	BUG_ON(!PageLocked(page));

@@ -414,6 +414,18 @@ retry_readpage:

 		return 0;

 	}

 	vi = page->mapping->host;

+	/*

+	 * If we've been called to read a zero sized inode, zero and bail.

+	 */

+	if (!once) {

+		loff_t i_size = i_size_read(vi);

+

+		once++;

+		if (!i_size) {

+			zero_user_page(page, 0, PAGE_CACHE_SIZE, KM_USER0);

+			goto done;

+		}

+	}

 	ni = NTFS_I(vi);

 	/*

 	 * Only $DATA attributes can be encrypted and only unnamed $DATA
-

Hi,
Yes that will fix it but the complete solution is more involved as

there are three related bugs which explain why you were getting the

hangs after the error...  I will make a patch for all of these in the

next few days...
Best regards,
--

Anton Altaparmakov <aia21 at cam.ac.uk> (replace at with @)

Unix Support, Computing Service, University of Cambridge, CB2 3QH, UK

Linux NTFS maintainer, http://www.linux-ntfs.org/
-

Hi Mike,
Attached is a patch that should fix this and the other related issues

I found.
Would you be able to test it in your setup?  Thanks a lot in advance!
Best regards,
	Anton

--

Anton Altaparmakov <aia21 at cam.ac.uk> (replace at with @)

Unix Support, Computing Service, University of Cambridge, CB2 3QH, UK

Linux NTFS maintainer, http://www.linux-ntfs.org/

Modulo uninitialized vi, works fine.  I moved it up, and all is well.

Thanks.
Tested-by:  Mike Galbraith <efault@gmx.de>
diff --git a/fs/ntfs/aops.c b/fs/ntfs/aops.c

index cfdc790..ad87cb0 100644

--- a/fs/ntfs/aops.c

+++ b/fs/ntfs/aops.c

@@ -405,6 +405,15 @@ static int ntfs_readpage(struct file *file, struct page *page)
 retry_readpage:

 	BUG_ON(!PageLocked(page));

+	vi = page->mapping->host;

+	i_size = i_size_read(vi);

+	/* Is the page fully outside i_size? (truncate in progress) */

+	if (unlikely(page->index >= (i_size + PAGE_CACHE_SIZE - 1) >>

+			PAGE_CACHE_SHIFT)) {

+		zero_user_page(page, 0, PAGE_CACHE_SIZE, KM_USER0);

+		ntfs_debug("Read outside i_size - truncated?");

+		goto done;

+	}

 	/*

 	 * This can potentially happen because we clear PageUptodate() during

 	 * ntfs_writepage() of MstProtected() attributes.

@@ -413,7 +422,6 @@ retry_readpage:

 		unlock_page(page);

 		return 0;

 	}

-	vi = page->mapping->host;

 	ni = NTFS_I(vi);

 	/*

 	 * Only $DATA attributes can be encrypted and only unnamed $DATA

diff --git a/fs/ntfs/attrib.c b/fs/ntfs/attrib.c

index 92dabdc..50d3b0c 100644

--- a/fs/ntfs/attrib.c

+++ b/fs/ntfs/attrib.c

@@ -179,10 +179,7 @@ int ntfs_map_runlist_nolock(ntfs_inode *ni, VCN vcn, ntfs_attr_search_ctx *ctx)

 	 * ntfs_mapping_pairs_decompress() fails.

 	 */

 	end_vcn = sle64_to_cpu(a->data.non_resident.highest_vcn) + 1;

-	if (!a->data.non_resident.lowest_vcn && end_vcn == 1)

-		end_vcn = sle64_to_cpu(a->data.non_resident.allocated_size) >>

-				ni->vol->cluster_size_bits;

-	if (unlikely(vcn >= end_vcn)) {

+	if (unlikely(vcn && vcn >= end_vcn)) {

 		err = -ENOENT;

 		goto err_out;

 	}

diff --git a/fs/ntfs/compress.c b/fs/ntfs/compress.c

index d98daf5..d1619d0 100644

--- a/fs/ntfs/compress.c

+++ b/fs/ntfs/compress.c

@@ -561,6 +561,16 @@ int ntfs_read_compressed_block(struct page *page)

 	read_unlock_irqrestore(&ni->size_lock, flags);

 	max_page = ((i_siz...
[ message continues ]

Great, thanks!  I will submit it to Linus.
Best regards,
	Anton
--

Anton Altaparmakov <aia21 at cam.ac.uk> (replace at with @)

Unix Support, Computing Service, University of Cambridge, CB2 3QH, UK

Linux NTFS maintainer, http://www.linux-ntfs.org/
-

oops. forgot to attach the patch...   Here it is...
Best regards,
	Anton

hrmph, CC to members only list removed.
-

What makes you think it is members only?!?  NTFS-dev is not members

only at all.  It is moderated which is a very different thing.  Most

list members have to be approved for posting, too...  And the only

reason it is moderated is spam filtering.  We delete 99.9% of emails

going to the list by hand as moderators because they are all spam.

That means the list and the list archives only contain NTFS related

messages and not thousands of posts trying to sell you pills and what

not...
Best regards,
--

Anton Altaparmakov <aia21 at cam.ac.uk> (replace at with @)

Unix Support, Computing Service, University of Cambridge, CB2 3QH, UK

Linux NTFS maintainer, http://www.linux-ntfs.org/
-