forked from luck/tmp_suning_uos_patched
befs: improve documentation in datastream.c
Convert function descriptions to kernel-doc style. Signed-off-by: Luis de Bethencourt <luisbg@osg.samsung.com> Signed-off-by: Salah Triki <salah.triki@gmail.com>
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Luis de Bethencourt
parent
d327e612bd
commit
a20af5f9ea
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@ -75,7 +75,13 @@ befs_read_datastream(struct super_block *sb, const befs_data_stream *ds,
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return bh;
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}
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/*
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/**
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* befs_fblock2brun - give back block run for fblock
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* @sb: the superblock
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* @data: datastream to read from
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* @fblock: the blocknumber with the file position to find
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* @run: The found run is passed back through this pointer
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*
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* Takes a file position and gives back a brun who's starting block
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* is block number fblock of the file.
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*
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@ -212,36 +218,35 @@ befs_count_blocks(struct super_block *sb, const befs_data_stream *ds)
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return blocks;
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}
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/*
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Finds the block run that starts at file block number blockno
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in the file represented by the datastream data, if that
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blockno is in the direct region of the datastream.
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sb: the superblock
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data: the datastream
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blockno: the blocknumber to find
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run: The found run is passed back through this pointer
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Return value is BEFS_OK if the blockrun is found, BEFS_ERR
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otherwise.
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Algorithm:
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Linear search. Checks each element of array[] to see if it
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contains the blockno-th filesystem block. This is necessary
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because the block runs map variable amounts of data. Simply
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keeps a count of the number of blocks searched so far (sum),
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incrementing this by the length of each block run as we come
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across it. Adds sum to *count before returning (this is so
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you can search multiple arrays that are logicaly one array,
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as in the indirect region code).
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When/if blockno is found, if blockno is inside of a block
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run as stored on disk, we offset the start and length members
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of the block run, so that blockno is the start and len is
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still valid (the run ends in the same place).
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2001-11-15 Will Dyson
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*/
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/**
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* befs_find_brun_direct - find a direct block run in the datastream
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* @sb: the superblock
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* @data: the datastream
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* @blockno: the blocknumber to find
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* @run: The found run is passed back through this pointer
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*
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* Finds the block run that starts at file block number blockno
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* in the file represented by the datastream data, if that
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* blockno is in the direct region of the datastream.
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*
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* Return value is BEFS_OK if the blockrun is found, BEFS_ERR
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* otherwise.
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*
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* Algorithm:
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* Linear search. Checks each element of array[] to see if it
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* contains the blockno-th filesystem block. This is necessary
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* because the block runs map variable amounts of data. Simply
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* keeps a count of the number of blocks searched so far (sum),
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* incrementing this by the length of each block run as we come
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* across it. Adds sum to *count before returning (this is so
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* you can search multiple arrays that are logicaly one array,
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* as in the indirect region code).
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*
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* When/if blockno is found, if blockno is inside of a block
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* run as stored on disk, we offset the start and length members
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* of the block run, so that blockno is the start and len is
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* still valid (the run ends in the same place).
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*/
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static int
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befs_find_brun_direct(struct super_block *sb, const befs_data_stream *data,
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befs_blocknr_t blockno, befs_block_run * run)
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@ -273,29 +278,28 @@ befs_find_brun_direct(struct super_block *sb, const befs_data_stream *data,
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return BEFS_ERR;
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}
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/*
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Finds the block run that starts at file block number blockno
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in the file represented by the datastream data, if that
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blockno is in the indirect region of the datastream.
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sb: the superblock
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data: the datastream
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blockno: the blocknumber to find
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run: The found run is passed back through this pointer
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Return value is BEFS_OK if the blockrun is found, BEFS_ERR
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otherwise.
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Algorithm:
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For each block in the indirect run of the datastream, read
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it in and search through it for search_blk.
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XXX:
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Really should check to make sure blockno is inside indirect
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region.
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2001-11-15 Will Dyson
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*/
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/**
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* befs_find_brun_indirect - find a block run in the datastream
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* @sb: the superblock
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* @data: the datastream
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* @blockno: the blocknumber to find
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* @run: The found run is passed back through this pointer
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*
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* Finds the block run that starts at file block number blockno
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* in the file represented by the datastream data, if that
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* blockno is in the indirect region of the datastream.
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*
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* Return value is BEFS_OK if the blockrun is found, BEFS_ERR
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* otherwise.
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*
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* Algorithm:
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* For each block in the indirect run of the datastream, read
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* it in and search through it for search_blk.
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*
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* XXX:
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* Really should check to make sure blockno is inside indirect
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* region.
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*/
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static int
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befs_find_brun_indirect(struct super_block *sb,
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const befs_data_stream *data,
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@ -365,47 +369,46 @@ befs_find_brun_indirect(struct super_block *sb,
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return BEFS_ERR;
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}
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/*
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Finds the block run that starts at file block number blockno
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in the file represented by the datastream data, if that
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blockno is in the double-indirect region of the datastream.
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sb: the superblock
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data: the datastream
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blockno: the blocknumber to find
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run: The found run is passed back through this pointer
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Return value is BEFS_OK if the blockrun is found, BEFS_ERR
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otherwise.
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Algorithm:
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The block runs in the double-indirect region are different.
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They are always allocated 4 fs blocks at a time, so each
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block run maps a constant amount of file data. This means
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that we can directly calculate how many block runs into the
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double-indirect region we need to go to get to the one that
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maps a particular filesystem block.
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We do this in two stages. First we calculate which of the
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inode addresses in the double-indirect block will point us
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to the indirect block that contains the mapping for the data,
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then we calculate which of the inode addresses in that
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indirect block maps the data block we are after.
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Oh, and once we've done that, we actually read in the blocks
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that contain the inode addresses we calculated above. Even
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though the double-indirect run may be several blocks long,
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we can calculate which of those blocks will contain the index
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we are after and only read that one. We then follow it to
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the indirect block and perform a similar process to find
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the actual block run that maps the data block we are interested
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in.
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Then we offset the run as in befs_find_brun_array() and we are
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done.
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2001-11-15 Will Dyson
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*/
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/**
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* befs_find_brun_dblindirect - find a block run in the datastream
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* @sb: the superblock
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* @data: the datastream
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* @blockno: the blocknumber to find
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* @run: The found run is passed back through this pointer
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*
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* Finds the block run that starts at file block number blockno
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* in the file represented by the datastream data, if that
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* blockno is in the double-indirect region of the datastream.
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*
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* Return value is BEFS_OK if the blockrun is found, BEFS_ERR
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* otherwise.
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*
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* Algorithm:
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* The block runs in the double-indirect region are different.
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* They are always allocated 4 fs blocks at a time, so each
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* block run maps a constant amount of file data. This means
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* that we can directly calculate how many block runs into the
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* double-indirect region we need to go to get to the one that
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* maps a particular filesystem block.
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*
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* We do this in two stages. First we calculate which of the
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* inode addresses in the double-indirect block will point us
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* to the indirect block that contains the mapping for the data,
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* then we calculate which of the inode addresses in that
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* indirect block maps the data block we are after.
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*
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* Oh, and once we've done that, we actually read in the blocks
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* that contain the inode addresses we calculated above. Even
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* though the double-indirect run may be several blocks long,
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* we can calculate which of those blocks will contain the index
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* we are after and only read that one. We then follow it to
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* the indirect block and perform a similar process to find
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* the actual block run that maps the data block we are interested
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* in.
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*
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* Then we offset the run as in befs_find_brun_array() and we are
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* done.
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*/
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static int
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befs_find_brun_dblindirect(struct super_block *sb,
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const befs_data_stream *data,
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