2  * mst.c - NTFS multi sector transfer protection handling code. Part of the
3  *	   Linux-NTFS project.
5  * Copyright (c) 2001-2004 Anton Altaparmakov
18  * along with this program (in the main directory of the Linux-NTFS
20  * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
26  * post_read_mst_fixup - deprotect multi sector transfer protected data
30  * Perform the necessary post read multi sector transfer fixup and detect the
31  * presence of incomplete multi sector transfers. - In that case, overwrite the
35  * Return 0 on success and -EINVAL on error ("BAAD" magic will be present).
48 	usa_ofs = le16_to_cpu(b->usa_ofs);  in post_read_mst_fixup()
50 	usa_count = le16_to_cpu(b->usa_count) - 1;  in post_read_mst_fixup()
52 	if ( size & (NTFS_BLOCK_SIZE - 1)	||  in post_read_mst_fixup()
63 	 * structures which means the data is consistent. - If it is  in post_read_mst_fixup()
70 	data_pos = (u16*)b + NTFS_BLOCK_SIZE/sizeof(u16) - 1;  in post_read_mst_fixup()
72 	 * Check for incomplete multi sector transfer(s).  in post_read_mst_fixup()
74 	while (usa_count--) {  in post_read_mst_fixup()
77 			 * Incomplete multi sector transfer detected! )-:  in post_read_mst_fixup()
81 			b->magic = magic_BAAD;  in post_read_mst_fixup()
82 			return -EINVAL;  in post_read_mst_fixup()
86 	/* Re-setup the variables. */  in post_read_mst_fixup()
87 	usa_count = le16_to_cpu(b->usa_count) - 1;  in post_read_mst_fixup()
88 	data_pos = (u16*)b + NTFS_BLOCK_SIZE/sizeof(u16) - 1;  in post_read_mst_fixup()
90 	while (usa_count--) {  in post_read_mst_fixup()
103  * pre_write_mst_fixup - apply multi sector transfer protection
107  * Perform the necessary pre write multi sector transfer fixup on the data
110  * Return 0 if fixup applied (success) or -EINVAL if no fixup was performed
116  * array header in the ntfs record before calling this function, otherwise it
119  * initialise the update sequence number before calling this function
130 	if (!b || ntfs_is_baad_record(b->magic) ||  in pre_write_mst_fixup()
131 			ntfs_is_hole_record(b->magic))  in pre_write_mst_fixup()
132 		return -EINVAL;  in pre_write_mst_fixup()
134 	usa_ofs = le16_to_cpu(b->usa_ofs);  in pre_write_mst_fixup()
136 	usa_count = le16_to_cpu(b->usa_count) - 1;  in pre_write_mst_fixup()
138 	if ( size & (NTFS_BLOCK_SIZE - 1)	||  in pre_write_mst_fixup()
142 		return -EINVAL;  in pre_write_mst_fixup()
147 	 * (skipping 0 and -1, i.e. 0xffff).  in pre_write_mst_fixup()
155 	data_pos = (le16*)b + NTFS_BLOCK_SIZE/sizeof(le16) - 1;  in pre_write_mst_fixup()
157 	while (usa_count--) {  in pre_write_mst_fixup()
172  * post_write_mst_fixup - fast deprotect multi sector transfer protected data
175  * Perform the necessary post write multi sector transfer fixup, not checking
183 	u16 usa_ofs = le16_to_cpu(b->usa_ofs);  in post_write_mst_fixup()
184 	u16 usa_count = le16_to_cpu(b->usa_count) - 1;  in post_write_mst_fixup()
190 	data_pos = (le16*)b + NTFS_BLOCK_SIZE/sizeof(le16) - 1;  in post_write_mst_fixup()
193 	while (usa_count--) {  in post_write_mst_fixup()