Re: stat64 for over 2TB file returned invalid st_blocks
From: Takashi Sato
Date: Tue Dec 06 2005 - 07:42:06 EST
Hi,
> > >> 2. Change the type of architecture dependent stat64.st_blocks in
> > >> include/asm/asm-*/stat.h from unsigned long to unsigned long long.
> > >> I tried modifying only stat64 of 32bit architecture
> > >> (include/asm-i386/stat.h).
> > >
> > >This changes the API, but the structure does suggest that the 4-byte pad
> > >should be used for the high-order bytes of st_blocks, so that's not
> > >really a problem. A correct fix would replace __pad4 with
> > >st_blocks_high (or something like that) and ensure that the high-order
> > >word was stored there. Your proposed fix would only be correct on
> > >little-endian hardware, as Jörn pointed out.
> >
> > Thank you for your advice. I'll research for glibc and consider
> > how to implement.
> > By the way I think, as Avi Kivity said, it's always little-endian on i386,
> > is it correct?
>
> That's true. The patch does fix i386 without any bad side-effects. A
> generic fix that would fix all architectures would be a little more
> complicated, since the size of st_blocks varies. 32-bit big-endian
> would have to explicitly copy the high and low words. (The first time I
> looked at this, I ignored the fact that the change was in asm-i386.)
I realized some 32-bit big-endian architectures such as sh and m68k
have a padding before 32-bit st_blocks, though mips and ppc have
64-bit st_blocks.
- asm-sh
#if defined(__BIG_ENDIAN__)
unsigned long __pad4; /* Future possible st_blocks hi bits */
unsigned long st_blocks; /* Number 512-byte blocks allocated. */
#else /* Must be little */
unsigned long st_blocks; /* Number 512-byte blocks allocated. */
unsigned long __pad4; /* Future possible st_blocks hi bits */
#endif
- asm-m68k
unsigned long __pad4; /* future possible st_blocks high bits */
unsigned long st_blocks; /* Number 512-byte blocks allocated. */
So I updated the patch. Any feedback and comments are welcome.
Signed-off-by: Takashi Sato <sho@xxxxxxxxxxxxxx>
Signed-off-by: ASANO Masahiro <masano@xxxxxxxxxxxxxx>
diff -uprN -X linux-2.6.15-rc5.org/Documentation/dontdiff linux-2.6.15-rc5.org/include/asm-i386/stat.h
linux-2.6.15-rc5-blocks/include/asm-i386/stat.h
--- linux-2.6.15-rc5.org/include/asm-i386/stat.h 2005-10-28 09:02:08.000000000 +0900
+++ linux-2.6.15-rc5-blocks/include/asm-i386/stat.h 2005-12-06 16:24:31.000000000 +0900
@@ -58,8 +58,7 @@ struct stat64 {
long long st_size;
unsigned long st_blksize;
- unsigned long st_blocks; /* Number 512-byte blocks allocated. */
- unsigned long __pad4; /* future possible st_blocks high bits */
+ unsigned long long st_blocks; /* Number 512-byte blocks allocated. */
unsigned long st_atime;
unsigned long st_atime_nsec;
diff -uprN -X linux-2.6.15-rc5.org/Documentation/dontdiff linux-2.6.15-rc5.org/include/asm-m68k/stat.h
linux-2.6.15-rc5-blocks/include/asm-m68k/stat.h
--- linux-2.6.15-rc5.org/include/asm-m68k/stat.h 2005-10-28 09:02:08.000000000 +0900
+++ linux-2.6.15-rc5-blocks/include/asm-m68k/stat.h 2005-12-06 16:29:50.000000000 +0900
@@ -60,8 +60,7 @@ struct stat64 {
long long st_size;
unsigned long st_blksize;
- unsigned long __pad4; /* future possible st_blocks high bits */
- unsigned long st_blocks; /* Number 512-byte blocks allocated. */
+ unsigned long long st_blocks; /* Number 512-byte blocks allocated. */
unsigned long st_atime;
unsigned long st_atime_nsec;
diff -uprN -X linux-2.6.15-rc5.org/Documentation/dontdiff linux-2.6.15-rc5.org/include/asm-sh/stat.h
linux-2.6.15-rc5-blocks/include/asm-sh/stat.h
--- linux-2.6.15-rc5.org/include/asm-sh/stat.h 2005-10-28 09:02:08.000000000 +0900
+++ linux-2.6.15-rc5-blocks/include/asm-sh/stat.h 2005-12-06 16:28:37.000000000 +0900
@@ -60,13 +60,7 @@ struct stat64 {
long long st_size;
unsigned long st_blksize;
-#if defined(__BIG_ENDIAN__)
- unsigned long __pad4; /* Future possible st_blocks hi bits */
- unsigned long st_blocks; /* Number 512-byte blocks allocated. */
-#else /* Must be little */
- unsigned long st_blocks; /* Number 512-byte blocks allocated. */
- unsigned long __pad4; /* Future possible st_blocks hi bits */
-#endif
+ unsigned long long st_blocks; /* Number 512-byte blocks allocated. */
unsigned long st_atime;
unsigned long st_atime_nsec;
diff -uprN -X linux-2.6.15-rc5.org/Documentation/dontdiff linux-2.6.15-rc5.org/include/linux/fs.h
linux-2.6.15-rc5-blocks/include/linux/fs.h
--- linux-2.6.15-rc5.org/include/linux/fs.h 2005-12-06 16:20:21.000000000 +0900
+++ linux-2.6.15-rc5-blocks/include/linux/fs.h 2005-12-06 16:26:01.000000000 +0900
@@ -450,7 +450,7 @@ struct inode {
unsigned int i_blkbits;
unsigned long i_blksize;
unsigned long i_version;
- unsigned long i_blocks;
+ unsigned long long i_blocks;
unsigned short i_bytes;
spinlock_t i_lock; /* i_blocks, i_bytes, maybe i_size */
struct semaphore i_sem;
diff -uprN -X linux-2.6.15-rc5.org/Documentation/dontdiff linux-2.6.15-rc5.org/include/linux/stat.h
linux-2.6.15-rc5-blocks/include/linux/stat.h
--- linux-2.6.15-rc5.org/include/linux/stat.h 2005-10-28 09:02:08.000000000 +0900
+++ linux-2.6.15-rc5-blocks/include/linux/stat.h 2005-12-06 16:26:26.000000000 +0900
@@ -69,7 +69,7 @@ struct kstat {
struct timespec mtime;
struct timespec ctime;
unsigned long blksize;
- unsigned long blocks;
+ unsigned long long blocks;
};
#endif
-- Takashi Sato
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