On Thu, Feb 24, 2011 at 8:03 PM, Lukas Czerner <lczerner@xxxxxxxxxx> wrote: > On Thu, 24 Feb 2011, Kyungmin Park wrote: > >> On Thu, Feb 24, 2011 at 5:53 PM, Lukas Czerner <lczerner@xxxxxxxxxx> wrote: >> > On Thu, 24 Feb 2011, Kyungmin Park wrote: >> > >> >> 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/ >> >> >> >> Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx> >> > >> > Hi Kyungmin, >> > thanks to second version. How did you test it ? You can try xtestest >> > 251 for simple verification. >> > I can not really comment on FAT specific code, however I have couple of >> > comments bellow. >> > >> > Thanks! >> > -Lukas >> > >> >> --- >> >> 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..ea31ee4 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); >> > ^^^^^^^^ >> > This patch does not pass checkpatch.pl script. Use tabs for indention. >> right, I will fix it. now passed the checkpatch.pl. >> >> > >> >> +} >> >> + >> >> 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 +691,88 @@ 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 = 0, free, count, entry; >> >> + int start, len, minlen, trimmed; >> >> + >> >> + start = range->start >> sb->s_blocksize_bits; >> >> + start = start / sbi->sec_per_clus; >> >> + len = range->len >> sb->s_blocksize_bits; >> >> + len = len / sbi->sec_per_clus; >> >> + minlen = range->minlen >> sb->s_blocksize_bits; >> >> + minlen = minlen / sbi->sec_per_clus; >> > >> > I should have mention that earlier, but you can also adjust mineln >> > according to the discard_granularity, because extents smaller than that >> > would not be discarded anyway. >> I adjust the minlen granularity with fat cluster unit. and FAT don't >> know what's the effected block size. it's role of user side. > > Actually it is not and you should check > request_queue->limits.discard_granularity Okay, it's simple one, I will add it. > > see: http://www.spinics.net/lists/linux-ext4/msg23145.html > >> > >> >> + trimmed = 0; >> >> + count = 0; >> >> + >> >> + 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; >> >> + >> >> + entry = 0; >> >> + free = 0; >> >> + fatent_init(&fatent); >> >> + >> >> + if (start < FAT_START_ENT) >> >> + start = FAT_START_ENT; >> > >> > You're not using start anywhere. >> > >> >> + >> >> + fatent_set_entry(&fatent, FAT_START_ENT); >> It should be fatent_set_entry(&fatent, start); >> >> + >> >> + while (count < sbi->max_cluster) { >> >> + if (fatent.entry >= sbi->max_cluster) >> >> + fatent.entry = FAT_START_ENT; >> >> + /* 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; >> >> + if (free >= (len - trimmed) && free >= minlen) { >> > >> > It seems to me that you are using len as number of bytes to trim. This >> > is not right and I am sorry for not explaining it correctly. "len" is >> > supposed to be a number of bytes you want to "investigate" from the start. >> > So it means that you will trim every single free extent bigger than minlen >> > between "start" byte and "start + len" byte of the underlying device, or >> > partition. >> No. len is adjusted at fat cluster number. it's not used byte unit. >> I think it's easy to compare with fat internal units. > > Does not matter what units are you using for len. I it just that you are > checking for (free >= (len - trimmed)) which is wrong because len is not > meant to be "overall length of trimmed data" but rather "overall length > of data to walk through and check for free extents" see ext4 > implementation for reference. I think I used it as you said. e.g., I want to trim 256 (* minimum discard granularity), First time, I can find 10 entries. and trimmed has 10 and len has still 256. next time, I found the 246 free entries then trim remaining 246 one. do you want to trim it more than given len? Thank you, Kyungmin Park > > Thanks! > -Lukas > >> >> I hope fat peoples comment this one. >> >> Thank you, >> Kyungmin Park >> > >> >> + fat_issue_discard(sb, entry, free); >> >> + trimmed += free; >> >> + } >> >> + if (trimmed >= len) >> >> + goto done; >> >> + } else if (entry) { >> >> + if (free >= minlen) { >> >> + fat_issue_discard(sb, entry, free); >> >> + trimmed += free; >> >> + } >> >> + if (trimmed >= len) >> >> + goto done; >> >> + free = 0; >> >> + entry = 0; >> >> + } >> >> + count++; >> >> + } while (fat_ent_next(sbi, &fatent)); >> >> + } >> >> + if (free >= minlen) { >> >> + fat_issue_discard(sb, entry, free); >> >> + trimmed += free; >> >> + } >> >> +done: >> >> + range->len = (trimmed * sbi->sec_per_clus) << sb->s_blocksize_bits; >> >> + fatent_brelse(&fatent); >> >> +out: >> >> + unlock_fat(sbi); >> >> + return err; >> >> +} >> >> diff --git a/fs/fat/file.c b/fs/fat/file.c >> >> index 7257752..05e6545 100644 >> >> --- a/fs/fat/file.c >> >> +++ b/fs/fat/file.c >> >> @@ -125,6 +125,34 @@ 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; >> >> + >> >> + 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 */ >> >> } >> >> >> > >> > -- >> > >> > > -- -- 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
