libext2fs: fix unix_io's Direct I/O support
The previous Direct I/O support worked on HDD's with 512 byte logical
sector sizes, and on FreeBSD which required 4k aligned memory buffers.
However, it was incomplete and was not correctly working on HDD's with
4k logical sector sizes (aka Advanced Format Disks).
Based on a patch from Alexey Lyashkov <alexey.lyashkov@hpe.com> but
rewritten to work with the latest e2fsprogs and to minimize changes to
make it easier to review.
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reported-by: Artem Blagodarenko <artem.blagodarenko@gmail.com>
diff --git a/lib/ext2fs/io_manager.c b/lib/ext2fs/io_manager.c
index c395d61..996c31a 100644
--- a/lib/ext2fs/io_manager.c
+++ b/lib/ext2fs/io_manager.c
@@ -134,9 +134,11 @@
else
size = -count;
- if (io->align)
+ if (io->align) {
+ if (io->align > size)
+ size = io->align;
return ext2fs_get_memalign(size, io->align, ptr);
- else
+ } else
return ext2fs_get_mem(size, ptr);
}
diff --git a/lib/ext2fs/unix_io.c b/lib/ext2fs/unix_io.c
index 73f5667..8965535 100644
--- a/lib/ext2fs/unix_io.c
+++ b/lib/ext2fs/unix_io.c
@@ -218,6 +218,8 @@
int actual = 0;
unsigned char *buf = bufv;
ssize_t really_read = 0;
+ unsigned long long aligned_blk;
+ int align_size, offset;
size = (count < 0) ? -count : (ext2_loff_t) count * channel->block_size;
mutex_lock(data, STATS_MTX);
@@ -226,7 +228,7 @@
location = ((ext2_loff_t) block * channel->block_size) + data->offset;
if (data->flags & IO_FLAG_FORCE_BOUNCE) {
- if (ext2fs_llseek(data->dev, location, SEEK_SET) != location) {
+ if (ext2fs_llseek(data->dev, location, SEEK_SET) < 0) {
retval = errno ? errno : EXT2_ET_LLSEEK_FAILED;
goto error_out;
}
@@ -237,6 +239,7 @@
/* Try an aligned pread */
if ((channel->align == 0) ||
(IS_ALIGNED(buf, channel->align) &&
+ IS_ALIGNED(location, channel->align) &&
IS_ALIGNED(size, channel->align))) {
actual = pread64(data->dev, buf, size, location);
if (actual == size)
@@ -248,6 +251,7 @@
if ((sizeof(off_t) >= sizeof(ext2_loff_t)) &&
((channel->align == 0) ||
(IS_ALIGNED(buf, channel->align) &&
+ IS_ALIGNED(location, channel->align) &&
IS_ALIGNED(size, channel->align)))) {
actual = pread(data->dev, buf, size, location);
if (actual == size)
@@ -256,12 +260,13 @@
}
#endif /* HAVE_PREAD */
- if (ext2fs_llseek(data->dev, location, SEEK_SET) != location) {
+ if (ext2fs_llseek(data->dev, location, SEEK_SET) < 0) {
retval = errno ? errno : EXT2_ET_LLSEEK_FAILED;
goto error_out;
}
if ((channel->align == 0) ||
(IS_ALIGNED(buf, channel->align) &&
+ IS_ALIGNED(location, channel->align) &&
IS_ALIGNED(size, channel->align))) {
actual = read(data->dev, buf, size);
if (actual != size) {
@@ -286,23 +291,39 @@
* to the O_DIRECT rules, so we need to do this the hard way...
*/
bounce_read:
+ if ((channel->block_size > channel->align) &&
+ (channel->block_size % channel->align) == 0)
+ align_size = channel->block_size;
+ else
+ align_size = channel->align;
+ aligned_blk = location / align_size;
+ offset = location % align_size;
+
+ if (ext2fs_llseek(data->dev, aligned_blk * align_size, SEEK_SET) < 0) {
+ retval = errno ? errno : EXT2_ET_LLSEEK_FAILED;
+ goto error_out;
+ }
while (size > 0) {
mutex_lock(data, BOUNCE_MTX);
- actual = read(data->dev, data->bounce, channel->block_size);
- if (actual != channel->block_size) {
+ actual = read(data->dev, data->bounce, align_size);
+ if (actual != align_size) {
mutex_unlock(data, BOUNCE_MTX);
actual = really_read;
buf -= really_read;
size += really_read;
goto short_read;
}
- actual = size;
- if (size > channel->block_size)
- actual = channel->block_size;
- memcpy(buf, data->bounce, actual);
+ if ((actual + offset) > align_size)
+ actual = align_size - offset;
+ if (actual > size)
+ actual = size;
+ memcpy(buf, data->bounce + offset, actual);
+
really_read += actual;
size -= actual;
buf += actual;
+ offset = 0;
+ aligned_blk++;
mutex_unlock(data, BOUNCE_MTX);
}
return 0;
@@ -326,6 +347,8 @@
int actual = 0;
errcode_t retval;
const unsigned char *buf = bufv;
+ unsigned long long aligned_blk;
+ int align_size, offset;
if (count == 1)
size = channel->block_size;
@@ -342,7 +365,7 @@
location = ((ext2_loff_t) block * channel->block_size) + data->offset;
if (data->flags & IO_FLAG_FORCE_BOUNCE) {
- if (ext2fs_llseek(data->dev, location, SEEK_SET) != location) {
+ if (ext2fs_llseek(data->dev, location, SEEK_SET) < 0) {
retval = errno ? errno : EXT2_ET_LLSEEK_FAILED;
goto error_out;
}
@@ -353,6 +376,7 @@
/* Try an aligned pwrite */
if ((channel->align == 0) ||
(IS_ALIGNED(buf, channel->align) &&
+ IS_ALIGNED(location, channel->align) &&
IS_ALIGNED(size, channel->align))) {
actual = pwrite64(data->dev, buf, size, location);
if (actual == size)
@@ -363,6 +387,7 @@
if ((sizeof(off_t) >= sizeof(ext2_loff_t)) &&
((channel->align == 0) ||
(IS_ALIGNED(buf, channel->align) &&
+ IS_ALIGNED(location, channel->align) &&
IS_ALIGNED(size, channel->align)))) {
actual = pwrite(data->dev, buf, size, location);
if (actual == size)
@@ -370,13 +395,14 @@
}
#endif /* HAVE_PWRITE */
- if (ext2fs_llseek(data->dev, location, SEEK_SET) != location) {
+ if (ext2fs_llseek(data->dev, location, SEEK_SET) < 0) {
retval = errno ? errno : EXT2_ET_LLSEEK_FAILED;
goto error_out;
}
if ((channel->align == 0) ||
(IS_ALIGNED(buf, channel->align) &&
+ IS_ALIGNED(location, channel->align) &&
IS_ALIGNED(size, channel->align))) {
actual = write(data->dev, buf, size);
if (actual < 0) {
@@ -400,40 +426,59 @@
* to the O_DIRECT rules, so we need to do this the hard way...
*/
bounce_write:
+ if ((channel->block_size > channel->align) &&
+ (channel->block_size % channel->align) == 0)
+ align_size = channel->block_size;
+ else
+ align_size = channel->align;
+ aligned_blk = location / align_size;
+ offset = location % align_size;
+
while (size > 0) {
+ int actual_w;
+
mutex_lock(data, BOUNCE_MTX);
- if (size < channel->block_size) {
+ if (size < align_size || offset) {
+ if (ext2fs_llseek(data->dev, aligned_blk * align_size,
+ SEEK_SET) < 0) {
+ retval = errno ? errno : EXT2_ET_LLSEEK_FAILED;
+ goto error_out;
+ }
actual = read(data->dev, data->bounce,
- channel->block_size);
- if (actual != channel->block_size) {
+ align_size);
+ if (actual != align_size) {
if (actual < 0) {
mutex_unlock(data, BOUNCE_MTX);
retval = errno;
goto error_out;
}
memset((char *) data->bounce + actual, 0,
- channel->block_size - actual);
+ align_size - actual);
}
}
actual = size;
- if (size > channel->block_size)
- actual = channel->block_size;
- memcpy(data->bounce, buf, actual);
- if (ext2fs_llseek(data->dev, location, SEEK_SET) != location) {
+ if ((actual + offset) > align_size)
+ actual = align_size - offset;
+ if (actual > size)
+ actual = size;
+ memcpy(((char *)data->bounce) + offset, buf, actual);
+ if (ext2fs_llseek(data->dev, aligned_blk * align_size, SEEK_SET) < 0) {
retval = errno ? errno : EXT2_ET_LLSEEK_FAILED;
goto error_out;
}
- actual = write(data->dev, data->bounce, channel->block_size);
+ actual_w = write(data->dev, data->bounce, align_size);
mutex_unlock(data, BOUNCE_MTX);
- if (actual < 0) {
+ if (actual_w < 0) {
retval = errno;
goto error_out;
}
- if (actual != channel->block_size)
+ if (actual_w != align_size)
goto short_write;
size -= actual;
buf += actual;
location += actual;
+ aligned_blk++;
+ offset = 0;
}
return 0;
