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Date: Sat, 9 Aug 2014 00:21:23 +0300
From: Timofey Titovets <nefelim4ag@...il.com>
To: unlisted-recipients:; (no To-header on input)
Cc: Ext4 Developers List <linux-ext4@...r.kernel.org>
Subject: Re: [PATCH] libext2fs: have UNIX IO manager use pread64/pwrite64
unsubscribe linux-ext4
2014-08-09 0:01 GMT+03:00 Theodore Ts'o <tytso@....edu>:
> Commit baa3544609da3c ("libext2fs: have UNIX IO manager use
> pread/pwrite) causes a breakage on 32-bit systems where off_t is
> 32-bits for file systems larger than 4GB. Fix this by using
> pread64/pwrite64 if possible, and if pread64/pwrite64 is not present,
> using pread/pwrite only if the size of off_t is at least as big as
> ext2_loff_t.
>
> Signed-off-by: Theodore Ts'o <tytso@....edu>
> ---
> configure | 2 +-
> configure.in | 2 ++
> lib/config.h.in | 6 ++++++
> lib/ext2fs/unix_io.c | 24 ++++++++++++++++++++++--
> 4 files changed, 31 insertions(+), 3 deletions(-)
>
> diff --git a/configure b/configure
> index f0af1d5..b9ce43d 100755
> --- a/configure
> +++ b/configure
> @@ -12994,7 +12994,7 @@ if test "$ac_res" != no; then :
> fi
>
> fi
> -for ac_func in __secure_getenv backtrace blkid_probe_get_topology blkid_probe_enable_partitions chflags fadvise64 fallocate fallocate64 fchown fdatasync fstat64 ftruncate64 futimes getcwd getdtablesize getmntinfo getpwuid_r getrlimit getrusage jrand48 llseek lseek64 mallinfo mbstowcs memalign mempcpy mmap msync nanosleep open64 pathconf posix_fadvise posix_fadvise64 posix_memalign prctl pread pwrite secure_getenv setmntent setresgid setresuid snprintf srandom stpcpy strcasecmp strdup strnlen strptime strtoull sync_file_range sysconf usleep utime valloc
> +for ac_func in __secure_getenv backtrace blkid_probe_get_topology blkid_probe_enable_partitions chflags fadvise64 fallocate fallocate64 fchown fdatasync fstat64 ftruncate64 futimes getcwd getdtablesize getmntinfo getpwuid_r getrlimit getrusage jrand48 llseek lseek64 mallinfo mbstowcs memalign mempcpy mmap msync nanosleep open64 pathconf posix_fadvise posix_fadvise64 posix_memalign prctl pread pwrite pread64 pwrite64 secure_getenv setmntent setresgid setresuid snprintf srandom stpcpy strcasecmp strdup strnlen strptime strtoull sync_file_range sysconf usleep utime valloc
> do :
> as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
> ac_fn_c_check_func "$LINENO" "$ac_func" "$as_ac_var"
> diff --git a/configure.in b/configure.in
> index b825f3d..2e59fde 100644
> --- a/configure.in
> +++ b/configure.in
> @@ -1061,6 +1061,8 @@ AC_CHECK_FUNCS(m4_flatten([
> prctl
> pread
> pwrite
> + pread64
> + pwrite64
> secure_getenv
> setmntent
> setresgid
> diff --git a/lib/config.h.in b/lib/config.h.in
> index 34fb0cc..50cf312 100644
> --- a/lib/config.h.in
> +++ b/lib/config.h.in
> @@ -328,6 +328,9 @@
> /* Define to 1 if you have the `pread' function. */
> #undef HAVE_PREAD
>
> +/* Define to 1 if you have the `pread64' function. */
> +#undef HAVE_PREAD64
> +
> /* Define if the <pthread.h> defines PTHREAD_MUTEX_RECURSIVE. */
> #undef HAVE_PTHREAD_MUTEX_RECURSIVE
>
> @@ -340,6 +343,9 @@
> /* Define to 1 if you have the `pwrite' function. */
> #undef HAVE_PWRITE
>
> +/* Define to 1 if you have the `pwrite64' function. */
> +#undef HAVE_PWRITE64
> +
> /* Define to 1 if dirent has d_reclen */
> #undef HAVE_RECLEN_DIRENT
>
> diff --git a/lib/ext2fs/unix_io.c b/lib/ext2fs/unix_io.c
> index 0dd1490..eb39b28 100644
> --- a/lib/ext2fs/unix_io.c
> +++ b/lib/ext2fs/unix_io.c
> @@ -131,11 +131,21 @@ static errcode_t raw_read_blk(io_channel channel,
> data->io_stats.bytes_read += size;
> location = ((ext2_loff_t) block * channel->block_size) + data->offset;
>
> -#ifdef HAVE_PREAD
> +#ifdef HAVE_PREAD64
> /* Try an aligned pread */
> if ((channel->align == 0) ||
> (IS_ALIGNED(buf, channel->align) &&
> IS_ALIGNED(size, channel->align))) {
> + actual = pread64(data->dev, buf, size, location);
> + if (actual == size)
> + return 0;
> + }
> +#elif HAVE_PREAD
> + /* Try an aligned pread */
> + if ((sizeof(off_t) >= sizeof(ext2_loff_t)) &&
> + ((channel->align == 0) ||
> + (IS_ALIGNED(buf, channel->align) &&
> + IS_ALIGNED(size, channel->align)))) {
> actual = pread(data->dev, buf, size, location);
> if (actual == size)
> return 0;
> @@ -213,11 +223,21 @@ static errcode_t raw_write_blk(io_channel channel,
>
> location = ((ext2_loff_t) block * channel->block_size) + data->offset;
>
> -#ifdef HAVE_PWRITE
> +#ifdef HAVE_PWRITE64
> /* Try an aligned pwrite */
> if ((channel->align == 0) ||
> (IS_ALIGNED(buf, channel->align) &&
> IS_ALIGNED(size, channel->align))) {
> + actual = pwrite64(data->dev, buf, size, location);
> + if (actual == size)
> + return 0;
> + }
> +#elif HAVE_PWRITE
> + /* Try an aligned pwrite */
> + if ((sizeof(off_t) >= sizeof(ext2_loff_t)) &&
> + ((channel->align == 0) ||
> + (IS_ALIGNED(buf, channel->align) &&
> + IS_ALIGNED(size, channel->align)))) {
> actual = pwrite(data->dev, buf, size, location);
> if (actual == size)
> return 0;
> --
> 2.0.0
>
> --
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--
Best regards,
Timofey.
--
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