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ntfs_attr_pwrite: write cluster size blocks if it's possible when expanding 

attributes. This will cause the kernel not to seek and read disk blocks for
filling the end of the buffer which increases write speed at least by 2-11
fold typically. (David Fox, Szabolcs Szakacsits)
master
szaka 2007-09-09 21:39:37 +00:00
parent d70399e3c4
commit a4277b3d0f
1 changed files with 31 additions and 5 deletions
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36
libntfs-3g/attrib.c
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@ -1281,11 +1281,37 @@ s64 ntfs_attr_pwrite(ntfs_attr *na, const s64 pos, s64 count, const void *b)
retry:
ntfs_log_trace("Writing %lld bytes to vcn %lld, lcn %lld, ofs "
"%lld.\n", to_write, rl->vcn, rl->lcn, ofs);
if (!NVolReadOnly(vol))
written = ntfs_pwrite(vol->dev, (rl->lcn <<
vol->cluster_size_bits) + ofs,
to_write, b);
else
if (!NVolReadOnly(vol)) {
s64 pos = (rl->lcn << vol->cluster_size_bits) + ofs;
int bsize = vol->cluster_size;
/*
* Write cluster size blocks if it's possible. This will
* cause the kernel not to seek and read disk blocks for
* filling the end of the buffer which increases write
* speed at least by 2-11 fold typically.
*/
if (!(ofs % bsize) && (to_write % bsize) &&
((ofs + to_write) == na->initialized_size)) {
s64 rounded = (to_write + bsize - 1) & ~(bsize - 1);
char *cb = ntfs_malloc(rounded);
if (!cb)
goto err_out;
memcpy(cb, b, to_write);
memset(cb + to_write, 0, rounded - to_write);
written = ntfs_pwrite(vol->dev, pos, rounded, cb);
if (written == rounded)
written = to_write;
free(cb);
} else
written = ntfs_pwrite(vol->dev, pos, to_write, b);
} else
written = to_write;
/* If everything ok, update progress counters and continue. */
if (written > 0) {