diff options
Diffstat (limited to 'fs/hpfs/buffer.c')
| -rw-r--r-- | fs/hpfs/buffer.c | 204 |
1 files changed, 204 insertions, 0 deletions
diff --git a/fs/hpfs/buffer.c b/fs/hpfs/buffer.c new file mode 100644 index 000000000..8057fe4e6 --- /dev/null +++ b/fs/hpfs/buffer.c @@ -0,0 +1,204 @@ +/* + * linux/fs/hpfs/buffer.c + * + * Mikulas Patocka (mikulas@artax.karlin.mff.cuni.cz), 1998-1999 + * + * general buffer i/o + */ +#include <linux/sched.h> +#include <linux/slab.h> +#include <linux/blkdev.h> +#include "hpfs_fn.h" + +void hpfs_prefetch_sectors(struct super_block *s, unsigned secno, int n) +{ + struct buffer_head *bh; + struct blk_plug plug; + + if (n <= 0 || unlikely(secno >= hpfs_sb(s)->sb_fs_size)) + return; + + bh = sb_find_get_block(s, secno); + if (bh) { + if (buffer_uptodate(bh)) { + brelse(bh); + return; + } + brelse(bh); + }; + + blk_start_plug(&plug); + while (n > 0) { + if (unlikely(secno >= hpfs_sb(s)->sb_fs_size)) + break; + sb_breadahead(s, secno); + secno++; + n--; + } + blk_finish_plug(&plug); +} + +/* Map a sector into a buffer and return pointers to it and to the buffer. */ + +void *hpfs_map_sector(struct super_block *s, unsigned secno, struct buffer_head **bhp, + int ahead) +{ + struct buffer_head *bh; + + hpfs_lock_assert(s); + + hpfs_prefetch_sectors(s, secno, ahead); + + cond_resched(); + + *bhp = bh = sb_bread(s, secno); + if (bh != NULL) + return bh->b_data; + else { + pr_err("%s(): read error\n", __func__); + return NULL; + } +} + +/* Like hpfs_map_sector but don't read anything */ + +void *hpfs_get_sector(struct super_block *s, unsigned secno, struct buffer_head **bhp) +{ + struct buffer_head *bh; + /*return hpfs_map_sector(s, secno, bhp, 0);*/ + + hpfs_lock_assert(s); + + cond_resched(); + + if ((*bhp = bh = sb_getblk(s, secno)) != NULL) { + if (!buffer_uptodate(bh)) wait_on_buffer(bh); + set_buffer_uptodate(bh); + return bh->b_data; + } else { + pr_err("%s(): getblk failed\n", __func__); + return NULL; + } +} + +/* Map 4 sectors into a 4buffer and return pointers to it and to the buffer. */ + +void *hpfs_map_4sectors(struct super_block *s, unsigned secno, struct quad_buffer_head *qbh, + int ahead) +{ + char *data; + + hpfs_lock_assert(s); + + cond_resched(); + + if (secno & 3) { + pr_err("%s(): unaligned read\n", __func__); + return NULL; + } + + hpfs_prefetch_sectors(s, secno, 4 + ahead); + + if (!(qbh->bh[0] = sb_bread(s, secno + 0))) goto bail0; + if (!(qbh->bh[1] = sb_bread(s, secno + 1))) goto bail1; + if (!(qbh->bh[2] = sb_bread(s, secno + 2))) goto bail2; + if (!(qbh->bh[3] = sb_bread(s, secno + 3))) goto bail3; + + if (likely(qbh->bh[1]->b_data == qbh->bh[0]->b_data + 1 * 512) && + likely(qbh->bh[2]->b_data == qbh->bh[0]->b_data + 2 * 512) && + likely(qbh->bh[3]->b_data == qbh->bh[0]->b_data + 3 * 512)) { + return qbh->data = qbh->bh[0]->b_data; + } + + qbh->data = data = kmalloc(2048, GFP_NOFS); + if (!data) { + pr_err("%s(): out of memory\n", __func__); + goto bail4; + } + + memcpy(data + 0 * 512, qbh->bh[0]->b_data, 512); + memcpy(data + 1 * 512, qbh->bh[1]->b_data, 512); + memcpy(data + 2 * 512, qbh->bh[2]->b_data, 512); + memcpy(data + 3 * 512, qbh->bh[3]->b_data, 512); + + return data; + + bail4: + brelse(qbh->bh[3]); + bail3: + brelse(qbh->bh[2]); + bail2: + brelse(qbh->bh[1]); + bail1: + brelse(qbh->bh[0]); + bail0: + return NULL; +} + +/* Don't read sectors */ + +void *hpfs_get_4sectors(struct super_block *s, unsigned secno, + struct quad_buffer_head *qbh) +{ + cond_resched(); + + hpfs_lock_assert(s); + + if (secno & 3) { + pr_err("%s(): unaligned read\n", __func__); + return NULL; + } + + if (!hpfs_get_sector(s, secno + 0, &qbh->bh[0])) goto bail0; + if (!hpfs_get_sector(s, secno + 1, &qbh->bh[1])) goto bail1; + if (!hpfs_get_sector(s, secno + 2, &qbh->bh[2])) goto bail2; + if (!hpfs_get_sector(s, secno + 3, &qbh->bh[3])) goto bail3; + + if (likely(qbh->bh[1]->b_data == qbh->bh[0]->b_data + 1 * 512) && + likely(qbh->bh[2]->b_data == qbh->bh[0]->b_data + 2 * 512) && + likely(qbh->bh[3]->b_data == qbh->bh[0]->b_data + 3 * 512)) { + return qbh->data = qbh->bh[0]->b_data; + } + + if (!(qbh->data = kmalloc(2048, GFP_NOFS))) { + pr_err("%s(): out of memory\n", __func__); + goto bail4; + } + return qbh->data; + +bail4: + brelse(qbh->bh[3]); +bail3: + brelse(qbh->bh[2]); +bail2: + brelse(qbh->bh[1]); +bail1: + brelse(qbh->bh[0]); +bail0: + return NULL; +} + + +void hpfs_brelse4(struct quad_buffer_head *qbh) +{ + if (unlikely(qbh->data != qbh->bh[0]->b_data)) + kfree(qbh->data); + brelse(qbh->bh[0]); + brelse(qbh->bh[1]); + brelse(qbh->bh[2]); + brelse(qbh->bh[3]); +} + +void hpfs_mark_4buffers_dirty(struct quad_buffer_head *qbh) +{ + if (unlikely(qbh->data != qbh->bh[0]->b_data)) { + memcpy(qbh->bh[0]->b_data, qbh->data + 0 * 512, 512); + memcpy(qbh->bh[1]->b_data, qbh->data + 1 * 512, 512); + memcpy(qbh->bh[2]->b_data, qbh->data + 2 * 512, 512); + memcpy(qbh->bh[3]->b_data, qbh->data + 3 * 512, 512); + } + mark_buffer_dirty(qbh->bh[0]); + mark_buffer_dirty(qbh->bh[1]); + mark_buffer_dirty(qbh->bh[2]); + mark_buffer_dirty(qbh->bh[3]); +} |