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.TH "EXT2_ALLOC_BRANCH" "" "06 October 2005" "" ""

.SH NAME
ext2_alloc_branch \- allocate and set up a chain of blocks.
.SH SYNOPSIS
"SYNOPSIS"
.sp
\fB
.sp
int ext2_alloc_branch  (struct inode * \fIinode\fB, int \fInum\fB, unsigned long \fIgoal\fB, int * \fIoffsets\fB, Indirect * \fIbranch\fB);
\fR
.SH "ARGUMENTS"
.TP
\fB\fIinode\fB\fR
owner
.TP
\fB\fInum\fB\fR
depth of the chain (number of blocks to allocate)
.TP
\fB\fIgoal\fB\fR
-- undescribed --
.TP
\fB\fIoffsets\fB\fR
offsets (in the blocks) to store the pointers to next.
.TP
\fB\fIbranch\fB\fR
place to store the chain in.
.SH "DESCRIPTION"
.PP
This function allocates \fInum\fR blocks, zeroes out all but the last one,
links them into chain and (if we are synchronous) writes them to disk.
In other words, it prepares a branch that can be spliced onto the
inode. It stores the information about that chain in the branch[], in
the same format as \fBext2_get_branch\fR would do. We are calling it after
we had read the existing part of chain and partial points to the last
triple of that (one with zero ->key). Upon the exit we have the same
picture as after the successful \fBext2_get_block\fR, excpet that in one
place chain is disconnected - *branch->p is still zero (we did not
set the last link), but branch->key contains the number that should
be placed into *branch->p to fill that gap.
.PP
If allocation fails we free all blocks we've allocated (and forget
their buffer_heads) and return the error value the from failed
\fBext2_alloc_block\fR (normally -ENOSPC). Otherwise we set the chain
as described above and return 0.