diff options
Diffstat (limited to 'fs/fat')
| -rw-r--r-- | fs/fat/fatent.c | 103 |
1 files changed, 75 insertions, 28 deletions
diff --git a/fs/fat/fatent.c b/fs/fat/fatent.c index 3647c65a0f48..bbfe18c07417 100644 --- a/fs/fat/fatent.c +++ b/fs/fat/fatent.c @@ -632,20 +632,80 @@ error: } EXPORT_SYMBOL_GPL(fat_free_clusters); -/* 128kb is the whole sectors for FAT12 and FAT16 */ -#define FAT_READA_SIZE (128 * 1024) +struct fatent_ra { + sector_t cur; + sector_t limit; + + unsigned int ra_blocks; + sector_t ra_advance; + sector_t ra_next; + sector_t ra_limit; +}; -static void fat_ent_reada(struct super_block *sb, struct fat_entry *fatent, - unsigned long reada_blocks) +static void fat_ra_init(struct super_block *sb, struct fatent_ra *ra, + struct fat_entry *fatent, int ent_limit) { - const struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops; - sector_t blocknr; - int i, offset; + struct msdos_sb_info *sbi = MSDOS_SB(sb); + const struct fatent_operations *ops = sbi->fatent_ops; + sector_t blocknr, block_end; + int offset; + /* + * This is the sequential read, so ra_pages * 2 (but try to + * align the optimal hardware IO size). + * [BTW, 128kb covers the whole sectors for FAT12 and FAT16] + */ + unsigned long ra_pages = sb->s_bdi->ra_pages; + unsigned int reada_blocks; + if (ra_pages > sb->s_bdi->io_pages) + ra_pages = rounddown(ra_pages, sb->s_bdi->io_pages); + reada_blocks = ra_pages << (PAGE_SHIFT - sb->s_blocksize_bits + 1); + + /* Initialize the range for sequential read */ ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr); + ops->ent_blocknr(sb, ent_limit - 1, &offset, &block_end); + ra->cur = 0; + ra->limit = (block_end + 1) - blocknr; - for (i = 0; i < reada_blocks; i++) - sb_breadahead(sb, blocknr + i); + /* Advancing the window at half size */ + ra->ra_blocks = reada_blocks >> 1; + ra->ra_advance = ra->cur; + ra->ra_next = ra->cur; + ra->ra_limit = ra->cur + min_t(sector_t, reada_blocks, ra->limit); +} + +/* Assuming to be called before reading a new block (increments ->cur). */ +static void fat_ent_reada(struct super_block *sb, struct fatent_ra *ra, + struct fat_entry *fatent) +{ + if (ra->ra_next >= ra->ra_limit) + return; + + if (ra->cur >= ra->ra_advance) { + struct msdos_sb_info *sbi = MSDOS_SB(sb); + const struct fatent_operations *ops = sbi->fatent_ops; + struct blk_plug plug; + sector_t blocknr, diff; + int offset; + + ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr); + + diff = blocknr - ra->cur; + blk_start_plug(&plug); + /* + * FIXME: we would want to directly use the bio with + * pages to reduce the number of segments. + */ + for (; ra->ra_next < ra->ra_limit; ra->ra_next++) + sb_breadahead(sb, ra->ra_next + diff); + blk_finish_plug(&plug); + + /* Advance the readahead window */ + ra->ra_advance += ra->ra_blocks; + ra->ra_limit += min_t(sector_t, + ra->ra_blocks, ra->limit - ra->ra_limit); + } + ra->cur++; } int fat_count_free_clusters(struct super_block *sb) @@ -653,27 +713,20 @@ int fat_count_free_clusters(struct super_block *sb) struct msdos_sb_info *sbi = MSDOS_SB(sb); const struct fatent_operations *ops = sbi->fatent_ops; struct fat_entry fatent; - unsigned long reada_blocks, reada_mask, cur_block; + struct fatent_ra fatent_ra; int err = 0, free; lock_fat(sbi); if (sbi->free_clusters != -1 && sbi->free_clus_valid) goto out; - reada_blocks = FAT_READA_SIZE >> sb->s_blocksize_bits; - reada_mask = reada_blocks - 1; - cur_block = 0; - free = 0; fatent_init(&fatent); fatent_set_entry(&fatent, FAT_START_ENT); + fat_ra_init(sb, &fatent_ra, &fatent, sbi->max_cluster); while (fatent.entry < sbi->max_cluster) { /* readahead of fat blocks */ - if ((cur_block & reada_mask) == 0) { - unsigned long rest = sbi->fat_length - cur_block; - fat_ent_reada(sb, &fatent, min(reada_blocks, rest)); - } - cur_block++; + fat_ent_reada(sb, &fatent_ra, &fatent); err = fat_ent_read_block(sb, &fatent); if (err) @@ -707,9 +760,9 @@ int fat_trim_fs(struct inode *inode, struct fstrim_range *range) struct msdos_sb_info *sbi = MSDOS_SB(sb); const struct fatent_operations *ops = sbi->fatent_ops; struct fat_entry fatent; + struct fatent_ra fatent_ra; u64 ent_start, ent_end, minlen, trimmed = 0; u32 free = 0; - unsigned long reada_blocks, reada_mask, cur_block = 0; int err = 0; /* @@ -727,19 +780,13 @@ int fat_trim_fs(struct inode *inode, struct fstrim_range *range) if (ent_end >= sbi->max_cluster) ent_end = sbi->max_cluster - 1; - reada_blocks = FAT_READA_SIZE >> sb->s_blocksize_bits; - reada_mask = reada_blocks - 1; - fatent_init(&fatent); lock_fat(sbi); fatent_set_entry(&fatent, ent_start); + fat_ra_init(sb, &fatent_ra, &fatent, ent_end + 1); while (fatent.entry <= ent_end) { /* readahead of fat blocks */ - if ((cur_block & reada_mask) == 0) { - unsigned long rest = sbi->fat_length - cur_block; - fat_ent_reada(sb, &fatent, min(reada_blocks, rest)); - } - cur_block++; + fat_ent_reada(sb, &fatent_ra, &fatent); err = fat_ent_read_block(sb, &fatent); if (err) |