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.TH "NTFS_READ_COMPRESSED_BLOCK" "9" "09 October 2005" "" ""

.SH NAME
ntfs_read_compressed_block \- read a compressed block into the page cache
.SH SYNOPSIS
"SYNOPSIS"
.sp
\fB
.sp
int ntfs_read_compressed_block  (struct page * \fIpage\fB);
\fR
.SH "ARGUMENTS"
.TP
\fB\fIpage\fB\fR
locked page in the compression block(s) we need to read
.SH "DESCRIPTION"
.PP
When we are called the page has already been verified to be locked and the
attribute is known to be non-resident, not encrypted, but compressed.
.PP
1. Determine which compression block(s) \fIpage\fR is in.
2. Get hold of all pages corresponding to this/these compression block(s).
3. Read the (first) compression block.
4. Decompress it into the corresponding pages.
5. Throw the compressed data away and proceed to 3. for the next compression
block or return success if no more compression blocks left.
.SH "WARNING"
.PP
We have to be careful what we do about existing pages. They might
have been written to so that we would lose data if we were to just overwrite
them with the out-of-date uncompressed data.
.SH "FIXME"
.PP
At the moment we don't do any zeroing out in the case that
initialized_size is less than data_size. This should be safe because of the
nature of the compression algorithm used. Just in case we check and output
an error message in read inode if the two sizes are not equal for a
compressed file. (AIA)
.SH "FIXME"
.PP
At the moment we don't do any zeroing out in the case that
initialized_size is less than data_size. This should be safe because of the
nature of the compression algorithm used. Just in case we check and output
an error message in read inode if the two sizes are not equal for a
compressed file. (AIA)
.SH "FIXME"
.PP
At the moment we don't do any zeroing out in the case that
initialized_size is less than data_size. This should be safe because of the
nature of the compression algorithm used. Just in case we check and output
an error message in read inode if the two sizes are not equal for a
compressed file. (AIA)