On Mon, Mar 28, 2011 at 12:39 AM, OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx> wrote: > Kyungmin Park <kmpark@xxxxxxxxxxxxx> writes: > >> From: Kyungmin Park <kyungmin.park@xxxxxxxxxxx> >> >> FAT supports batched discard as ext4. >> >> Cited from Lukas words. >> "The current solution is not ideal because of its bad performance impact. >> So basic idea to improve things is to avoid discarding every time some >> blocks are freed. and instead batching is together into bigger trims, >> which tends to be more effective." >> >> You can find an information in detail at following URLs. >> http://lwn.net/Articles/397538/ >> http://lwn.net/Articles/383933/ >> >> Clearify the meaning of "len" (Cited form Lukas mail) >> >> Let the "O" be free (bytes, blocks, whatever), and "=" be used. >> Now, we have a filesystem like this. >> >> OOOO==O===OO===OOOOO==O===O===OOOOOOO=== >> ^ ^ >> 0 40 >> >> This is how it supposed to wotk if you have called FITIRM with parameters: >> >> start = 0 >> minlen = 2 >> len = 20 >> >> So you will go through (blocks, bytes...) 0 -> 20 >> >> OOOO==O===OO===OOOOO==O===O===OOOOOOO=== >> ^ ^ >> 0 20 >> >> So, you will call discard on extents: >> >> 0-3 >> You'll skip 6 because is smaller than minlen >> 10-11 >> 15-19 >> >> instead of >> >> 0-3 >> 10-11 >> 15-19 >> 30-36 >> >> Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx> >> --- >> Changelog v5: >> Exit when start cluster is grater than max cluster >> >> Changelog v4: >> Simplify the exit condition >> >> Changelog v3: >> Adjust the minlen from queue discard_granularity >> Use the corrent len usage >> Changelog v2: >> Use the given start and len as Lukas comments >> Check the queue supports discard feature >> --- >> diff --git a/fs/fat/fat.h b/fs/fat/fat.h >> index f504089..08b53e1 100644 >> --- a/fs/fat/fat.h >> +++ b/fs/fat/fat.h >> @@ -299,6 +299,7 @@ extern int fat_alloc_clusters(struct inode *inode, int *cluster, >> int nr_cluster); >> extern int fat_free_clusters(struct inode *inode, int cluster); >> extern int fat_count_free_clusters(struct super_block *sb); >> +extern int fat_trim_fs(struct super_block *sb, struct fstrim_range *range); >> >> /* fat/file.c */ >> extern long fat_generic_ioctl(struct file *filp, unsigned int cmd, >> diff --git a/fs/fat/fatent.c b/fs/fat/fatent.c >> index b47d2c9..cc89ea6 100644 >> --- a/fs/fat/fatent.c >> +++ b/fs/fat/fatent.c >> @@ -1,6 +1,8 @@ >> /* >> * Copyright (C) 2004, OGAWA Hirofumi >> * Released under GPL v2. >> + * >> + * Batched discard support by Kyungmin Park <kyungmin.park@xxxxxxxxxxx> >> */ >> >> #include <linux/module.h> >> @@ -541,6 +543,16 @@ out: >> return err; >> } >> >> +static int fat_issue_discard(struct super_block *sb, int cluster, int nr_clus) >> +{ >> + struct msdos_sb_info *sbi = MSDOS_SB(sb); >> + sector_t block, nr_blocks; >> + >> + block = fat_clus_to_blknr(sbi, cluster); >> + nr_blocks = nr_clus * sbi->sec_per_clus; >> + return sb_issue_discard(sb, block, nr_blocks, GFP_NOFS, 0); >> +} >> + >> int fat_free_clusters(struct inode *inode, int cluster) >> { >> struct super_block *sb = inode->i_sb; >> @@ -575,11 +587,7 @@ int fat_free_clusters(struct inode *inode, int cluster) >> if (cluster != fatent.entry + 1) { >> int nr_clus = fatent.entry - first_cl + 1; >> >> - sb_issue_discard(sb, >> - fat_clus_to_blknr(sbi, first_cl), >> - nr_clus * sbi->sec_per_clus, >> - GFP_NOFS, 0); >> - >> + fat_issue_discard(sb, first_cl, nr_clus); >> first_cl = cluster; >> } >> } >> @@ -683,3 +691,86 @@ out: >> unlock_fat(sbi); >> return err; >> } >> + >> +int fat_trim_fs(struct super_block *sb, struct fstrim_range *range) >> +{ >> + struct msdos_sb_info *sbi = MSDOS_SB(sb); >> + struct fatent_operations *ops = sbi->fatent_ops; >> + struct fat_entry fatent; >> + unsigned long reada_blocks, reada_mask, cur_block; >> + int err, free, count, entry; >> + int start, len, minlen, trimmed; >> + >> + start = range->start >> sb->s_blocksize_bits; >> + start = start / sbi->sec_per_clus; > > start is round-down, I think it's strange interface. E.g. user specified > the range as "start=10 len=1024". So the range should be 10-1034, > i.e. (assume cluster-size is 512) 512-1024, right? I don't know what's the correct way? If you're right. it's better to round-up. If cluster-size is 32KiB and start sector is in the middle of cluster, then which is better. round-down or round-up? > >> + len = range->len >> sb->s_blocksize_bits; >> + len = len / sbi->sec_per_clus; > > And the end cluster should be round_down(start+len), right? > i.e. start=10 len=1014, the end should be 1024 not 512. will fix it. > >> + minlen = range->minlen >> sb->s_blocksize_bits; >> + minlen = minlen / sbi->sec_per_clus; >> + trimmed = 0; >> + count = 0; >> + err = -EINVAL; >> + >> + lock_fat(sbi); >> + if (sbi->free_clusters != -1 && sbi->free_clus_valid) >> + goto out; > > free clusters count validation doesn't matter here. If you want to check > free cluster count, you should check free_clusters==0 or not (after > validation). I borrowed it from "fat_count_free_clusters()". anyway fill fix it. > >> + if (start >= sbi->max_cluster) >> + goto out; > > This check can be done outside lock. And don't we need to check other > parameters from userland? I refereed it from ext4. it checked at ext4 codes. > >> + if (start < FAT_START_ENT) >> + start = FAT_START_ENT; > > Valid data cluster is 2 - max_cluster, but it should be mapped to 0 - > (max_cluster - FAT_START_ENT). Otherwise this interface's abstraction is > useless, right? user program don't know the filesystem internals. The same program is used for ext4 and fat. so it should be handled at filesystem. > >> + fatent_set_entry(&fatent, start); >> + >> + while (count < sbi->max_cluster) { >> + if (fatent.entry >= sbi->max_cluster) >> + fatent.entry = FAT_START_ENT; > > Why do we cyclic this? If the start is middle and len is the whole disk size, then check the all clusters. > >> + /* 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++; >> + >> + err = fat_ent_read_block(sb, &fatent); >> + if (err) >> + goto out; >> + >> + do { >> + if (ops->ent_get(&fatent) == FAT_ENT_FREE) { >> + free++; >> + if (!entry) >> + entry = fatent.entry; >> + } else if (entry) { >> + if (free >= minlen) { >> + fat_issue_discard(sb, entry, free); >> + trimmed += free; >> + } >> + free = 0; >> + entry = 0; >> + } >> + count++; >> + if (count >= len) >> + goto done; >> + } while (fat_ent_next(sbi, &fatent)); >> + } >> +done: >> + if (free >= minlen) { >> + fat_issue_discard(sb, entry, free); >> + trimmed += free; >> + } >> + range->len = (trimmed * sbi->sec_per_clus) << sb->s_blocksize_bits; > > this doesn't need cast? > > range->len = (u64)(trimmed * sbi->sec_per_clus) << sb->s_blocksize_bits; will fix it. > >> + fatent_brelse(&fatent); >> +out: >> + unlock_fat(sbi); >> + return err; >> +} >> diff --git a/fs/fat/file.c b/fs/fat/file.c >> index 7257752..9910aba 100644 >> --- a/fs/fat/file.c >> +++ b/fs/fat/file.c >> @@ -125,6 +125,36 @@ long fat_generic_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) >> return fat_ioctl_get_attributes(inode, user_attr); >> case FAT_IOCTL_SET_ATTRIBUTES: >> return fat_ioctl_set_attributes(filp, user_attr); >> + case FITRIM: >> + { >> + struct super_block *sb = inode->i_sb; >> + struct request_queue *q = bdev_get_queue(sb->s_bdev); >> + struct fstrim_range range; >> + int ret = 0; >> + >> + if (!capable(CAP_SYS_ADMIN)) >> + return -EPERM; >> + >> + if (!blk_queue_discard(q)) >> + return -EOPNOTSUPP; >> + >> + if (copy_from_user(&range, (struct fstrim_range *)arg, >> + sizeof(range))) >> + return -EFAULT; > > Please use __user annotation. Okay > >> + range.minlen = max((unsigned int)range.minlen, >> + q->limits.discard_granularity); > > Please use max_t() instead. Okay > >> + ret = fat_trim_fs(sb, &range); >> + if (ret < 0) >> + return ret; >> + >> + if (copy_to_user((struct fstrim_range *)arg, &range, >> + sizeof(range))) >> + return -EFAULT; >> + >> + return 0; >> + } >> + >> default: >> return -ENOTTY; /* Inappropriate ioctl for device */ >> } > > This doesn't need compat_ioctl? I'm not sure it's needed? I don't see other filesystem does. Thank you, Kyungmin Park > > Thanks. > -- > OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx> > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
