Re: [PATCH] ReiserFS file.c several bug-fix

Re: [PATCH] ReiserFS file.c several bug-fix

[Vladimir Saveliev]

Hello

On Thu, 2005-06-23 at 23:27, fs wrote:
> Related FS:
>     ReiserFS
> 
> Related Files:
>     fs/reiserfs/file.c
> 
> Bug description:
>     Make a ReiserFS partition in USB storage HDD, create a test file
> with enough size.
>     Write a program, do: open(O_SYNC/O_DSYNC) - read - close. After each
> operation, pause for a while, such as 3s. Between open and read, unlug
> the USB wire. open returns zero-filled buffer, no error returns.
> 
Open returns not buffer buf opened file descriptor or -1. Please
describe your test more carefully.


> Bug analysis:
>     reiserfs_file_write will claim some blocks, commit the I/O request,

So, you said: open(O_SYNC/O_DSYNC) - read - close. Where does write come
from?

> if O_SYNC and O_DSYNC is used, it will
>     if ((file->f_flags & O_SYNC) || IS_SYNC(inode))
> 	res = generic_osync_inode(inode, file->f_mapping,
>                                   OSYNC_METADATA|OSYNC_DATA);
> The question is, if I/O error occurs, 	    
>         res = reiserfs_allocate_blocks_for_region fails with -EIO, so
> it will exit the loop, no I/O request, no page marked as dirty.
> If run generic_osync_inode, it returns 0(no dirty page), res will be
> overwritten from -EIO to 0, thus no error report.
> 
> Also,  reiserfs_file_write contains a serious bug, see here
> 	blocks_to_allocate = reiserfs_prepare_file_region_for_write
> 		(inode, pos, num_pages, write_bytes, prepared_pages);
> Here blocks_to_allocate is defined as size_t, i.e. unsigned int, but
> reiserfs_prepare_file_region_for_write is declared as int, so sometimes
> it will return -EIO, -ENOENT, etc, take a look at this line
> 	if ( blocks_to_allocate < 0 ) { <- This will never happen
> 	    res = blocks_to_allocate;
> 	    reiserfs_release_claimed_blocks(inode->i_sb, 
> 		num_pages << (PAGE_CACHE_SHIFT - inode->i_blkbits));
> 	    break;
> 	}
> 
> Way around:
> 1) if already_written is zero, don't do generic_osync_inode
> 2) tell the result of reiserfs_prepare_file_region_for_write with IS_ERR
>    macro or cast it to size_t
> 
> Signed-off-by: Qu Fuping<fs@ercist.iscas.ac.cn>
> 
> Patch:
> diff -uNp linux-2.6.12/fs/reiserfs/file.c
> linux-2.6.12-new/fs/reiserfs/file.c
> 
> 

Re: [iscas-linaccident 55] Re: [PATCH] ReiserFS file.c several bug-fix

[qufuping]

----- Original Message ----- 
From: "Vladimir Saveliev" <vs@namesys.com>
To: "fs" <fs@ercist.iscas.ac.cn>
Cc: "reiserfs-list" <reiserfs-list@namesys.com>; "Hans Reiser" <reiser@namesys.com>; "iscas-linaccident" <iscas-linaccident@intellilink.co.jp>
Sent: Thursday, June 23, 2005 5:16 PM
Subject: [iscas-linaccident 55] Re: [PATCH] ReiserFS file.c several bug-fix


> Hello
> 
> On Thu, 2005-06-23 at 23:27, fs wrote:
> > Related FS:
> >     ReiserFS
> > 
> > Related Files:
> >     fs/reiserfs/file.c
> > 
> > Bug description:
> >     Make a ReiserFS partition in USB storage HDD, create a test file
> > with enough size.
> >     Write a program, do: open(O_SYNC/O_DSYNC) - read - close. After each

> > operation, pause for a while, such as 3s. Between open and read, unlug
                                                  
> > the USB wire. open returns zero-filled buffer, no error returns.
> > 

> Open returns not buffer buf opened file descriptor or -1. Please
> describe your test more carefully.
> 

Sorry to use the wrong template. :( 
Bug description:
      Make a ReiserFS partition in USB storage HDD, create a test file, 
for example, 64K. 
      Write a program, do: open(O_SYNC or O_DSYNC) - write(no need to use lseek)
 - close. After each operation, pause for a while, such as 3s. Between open
and write, unplug the USB wire. write returns no error.

> > Bug analysis:
> >     reiserfs_file_write will claim some blocks, commit the I/O request,
> 
> So, you said: open(O_SYNC/O_DSYNC) - read - close. Where does write come
> from?
> 
> > if O_SYNC and O_DSYNC is used, it will
> >     if ((file->f_flags & O_SYNC) || IS_SYNC(inode))
> > res = generic_osync_inode(inode, file->f_mapping,
> >                                   OSYNC_METADATA|OSYNC_DATA);
> > The question is, if I/O error occurs,     
> >         res = reiserfs_allocate_blocks_for_region fails with -EIO, so
> > it will exit the loop, no I/O request, no page marked as dirty.
> > If run generic_osync_inode, it returns 0(no dirty page), res will be
> > overwritten from -EIO to 0, thus no error report.
> > 
> > Also,  reiserfs_file_write contains a serious bug, see here
> > blocks_to_allocate = reiserfs_prepare_file_region_for_write
> > (inode, pos, num_pages, write_bytes, prepared_pages);
> > Here blocks_to_allocate is defined as size_t, i.e. unsigned int, but
> > reiserfs_prepare_file_region_for_write is declared as int, so sometimes
> > it will return -EIO, -ENOENT, etc, take a look at this line
> > if ( blocks_to_allocate < 0 ) { <- This will never happen
> >     res = blocks_to_allocate;
> >     reiserfs_release_claimed_blocks(inode->i_sb, 
> > num_pages << (PAGE_CACHE_SHIFT - inode->i_blkbits));
> >     break;
> > }

> > Way around:
> > 1) if already_written is zero, don't do generic_osync_inode
> > 2) tell the result of reiserfs_prepare_file_region_for_write with IS_ERR
> >    macro or cast it to size_t
> > 
> > Signed-off-by: Qu Fuping<fs@ercist.iscas.ac.cn>
> > 
> > Patch:
> > diff -uNp linux-2.6.12/fs/reiserfs/file.c
> > linux-2.6.12-new/fs/reiserfs/file.c
> > 
> > 
> 
> 

[PATCH] ReiserFS file.c several bug-fix

[fs]

[-- Attachment #1: Type: text/plain, Size: 1869 bytes --]

Related FS:
    ReiserFS

Related Files:
    fs/reiserfs/file.c

Bug description:
    Make a ReiserFS partition in USB storage HDD, create a test file
with enough size.
    Write a program, do: open(O_SYNC/O_DSYNC) - read - close. After each
operation, pause for a while, such as 3s. Between open and read, unlug
the USB wire. open returns zero-filled buffer, no error returns.

Bug analysis:
    reiserfs_file_write will claim some blocks, commit the I/O request,
if O_SYNC and O_DSYNC is used, it will
    if ((file->f_flags & O_SYNC) || IS_SYNC(inode))
	res = generic_osync_inode(inode, file->f_mapping,
                                  OSYNC_METADATA|OSYNC_DATA);
The question is, if I/O error occurs, 	    
        res = reiserfs_allocate_blocks_for_region fails with -EIO, so
it will exit the loop, no I/O request, no page marked as dirty.
If run generic_osync_inode, it returns 0(no dirty page), res will be
overwritten from -EIO to 0, thus no error report.

Also,  reiserfs_file_write contains a serious bug, see here
	blocks_to_allocate = reiserfs_prepare_file_region_for_write
		(inode, pos, num_pages, write_bytes, prepared_pages);
Here blocks_to_allocate is defined as size_t, i.e. unsigned int, but
reiserfs_prepare_file_region_for_write is declared as int, so sometimes
it will return -EIO, -ENOENT, etc, take a look at this line
	if ( blocks_to_allocate < 0 ) { <- This will never happen
	    res = blocks_to_allocate;
	    reiserfs_release_claimed_blocks(inode->i_sb, 
		num_pages << (PAGE_CACHE_SHIFT - inode->i_blkbits));
	    break;
	}

Way around:
1) if already_written is zero, don't do generic_osync_inode
2) tell the result of reiserfs_prepare_file_region_for_write with IS_ERR
   macro or cast it to size_t

Signed-off-by: Qu Fuping<fs@ercist.iscas.ac.cn>

Patch:
diff -uNp linux-2.6.12/fs/reiserfs/file.c
linux-2.6.12-new/fs/reiserfs/file.c



[-- Attachment #2: reiserfs_write.diff --]
[-- Type: text/x-patch, Size: 1628 bytes --]

--- linux-2.6.12/fs/reiserfs/file.c	2005-06-23 14:59:27.000000000 -0400
+++ linux-2.6.12-new/fs/reiserfs/file.c	2005-06-23 15:18:09.000000000 -0400
@@ -225,12 +225,6 @@ static int reiserfs_allocate_blocks_for_
     hint.preallocate = will_prealloc;
 
     /* Call block allocator to allocate blocks */
-    res = reiserfs_allocate_blocknrs(&hint, allocated_blocks, blocks_to_allocate, blocks_to_allocate);
-    if ( res != CARRY_ON ) {
-	if ( res == NO_DISK_SPACE ) {
-	    /* We flush the transaction in case of no space. This way some
-	       blocks might become free */
-	    SB_JOURNAL(inode->i_sb)->j_must_wait = 1;
 	    res = restart_transaction(th, inode, &path);
             if (res)
                 goto error_exit;
@@ -1306,7 +1300,7 @@ static ssize_t reiserfs_file_write( stru
 	   so that nobody else can access these until we are done.
 	   We get number of actual blocks needed as a result.*/
 	blocks_to_allocate = reiserfs_prepare_file_region_for_write(inode, pos, num_pages, write_bytes, prepared_pages);
-	if ( blocks_to_allocate < 0 ) {
+	if ( IS_ERROR((const void *)blocks_to_allocate) ) {
 	    res = blocks_to_allocate;
 	    reiserfs_release_claimed_blocks(inode->i_sb, num_pages << (PAGE_CACHE_SHIFT - inode->i_blkbits));
 	    break;
@@ -1363,6 +1357,10 @@ static ssize_t reiserfs_file_write( stru
         }
     }
 
+    /* If nothing is written, no need(actually, mustn't) to sync pages, just return res */
+    if( already_written == 0 )
+	    goto out;
+    
     if ((file->f_flags & O_SYNC) || IS_SYNC(inode))
 	res = generic_osync_inode(inode, file->f_mapping, OSYNC_METADATA|OSYNC_DATA);