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.TH "EXT2_GET_BRANCH" "9" "09 October 2005" "" ""

.SH NAME
ext2_get_branch \- read the chain of indirect blocks leading to data
.SH SYNOPSIS
"SYNOPSIS"
.sp
\fB
.sp
Indirect * ext2_get_branch  (struct inode * \fIinode\fB, int \fIdepth\fB, int * \fIoffsets\fB, Indirect \fIchain[4]\fB, int * \fIerr\fB);
\fR
.SH "ARGUMENTS"
.TP
\fB\fIinode\fB\fR
inode in question
.TP
\fB\fIdepth\fB\fR
depth of the chain (1 - direct pointer, etc.)
.TP
\fB\fIoffsets\fB\fR
offsets of pointers in inode/indirect blocks
.TP
\fB\fIchain[4]\fB\fR
place to store the result
.TP
\fB\fIerr\fB\fR
here we store the error value
.SH "DESCRIPTION"
.PP
Function fills the array of triples <key, p, bh> and returns NULL
if everything went OK or the pointer to the last filled triple
(incomplete one) otherwise. Upon the return chain[i].key contains
the number of (i+1)-th block in the chain (as it is stored in memory,
i.e. little-endian 32-bit), chain[i].p contains the address of that
number (it points into struct inode for i==0 and into the bh->b_data
for i>0) and chain[i].bh points to the buffer_head of i-th indirect
block for i>0 and NULL for i==0. In other words, it holds the block
numbers of the chain, addresses they were taken from (and where we can
verify that chain did not change) and buffer_heads hosting these
numbers.
.PP
Function stops when it stumbles upon zero pointer (absent block)
(pointer to last triple returned, *\fIerr\fR == 0)
or when it gets an IO error reading an indirect block
(ditto, *\fIerr\fR == -EIO)
or when it notices that chain had been changed while it was reading
(ditto, *\fIerr\fR == -EAGAIN)
or when it reads all \fIdepth\fR-1 indirect blocks successfully and finds
the whole chain, all way to the data (returns NULL, *err == 0).