On Mon, 28 Feb 2011, Kyungmin Park wrote: > On Fri, Feb 25, 2011 at 8:17 PM, Lukas Czerner <lczerner@xxxxxxxxxx> wrote: > > On Fri, 25 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/ > >> > >> 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 > > > > Hi thanks for the next version. And again I have to ask: Did you test it > > ? and how ? Did you tried xfstest No. 251 ? Couple of comments bellow. > > I tested it with your test program. Of course I modified for our > environment (eMMC). Ok, good. > > #include <errno.h> > #include <fcntl.h> > #include <stdio.h> > #include <stdint.h> > #include <sys/ioctl.h> > > struct fstrim_range { > uint64_t start; > uint64_t len; > uint64_t minlen; > }; > > #define FITRIM _IOWR('X', 121, struct fstrim_range) > > int main(int argc, char **argv) > { > struct fstrim_range range; > uint64_t len; > int fd; > > if (argc < 2) { > fprintf(stderr, "usage: %s mountpoint [size]\n", argv[0]); > return 1; > } > > if (argc == 3) > len = atoll(argv[1]); > else > len = ((1UL<<31) - 1); > > range.start = 0; > range.len = len; > range.minlen = 256 * 1024; /* Minimum is 256KiB */ Why exactly you need to set this ? What will happen if the minlen is 0 ? > > fd = open(argv[1], O_RDONLY); > if (fd < 0) { > perror("open"); > return 1; > } > > if (ioctl(fd, FITRIM, &range)) { > if (errno == EOPNOTSUPP) > fprintf(stderr, "TRIM not supported\n"); > else > perror("FITRIM"); > return 1; > } > > fprintf(stderr, "Trimmed size %llu\n", range.len); > > return 0; > } > > > > > Thanks! > > -Lukas > > > >> > >> Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx> > >> --- > >> 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..a8e3837 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 +691,88 @@ 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; > >> + 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; > >> + > >> + 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)); > > > > You really do not need new variable "rest" just for passing it into one > > function. Get rid of it. > > Umm. I don't want to modify it since it's routine is same as > free_count codes. I just borrowed it from FAT codes. > > > >> + } > >> + 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 (count >= len && free >= minlen) { > >> + fat_issue_discard(sb, entry, free); > >> + trimmed += free; I think you can remove this condition completely is you move "done" label befor the if (free >= minlen) condition. > > I really do not understand FAT code very much, but is this right ? > > Should not you be setting free = 0 ? > Right but count is larger then "len". it will exit at next if (count > >= len) goto done statement. Oh, ok I see. But it proves my point that this code is not very well readable. > > > What will happen if you'll end up > > in the same branch in next iteration ? -- free will be still set to > > previous value+1, bu you'll be discarding next entry. I am sorry but > > this whole thing is not very readable. > > > > >> + } > >> + if (count >= len) > >> + goto done; ^^^^^^^^^^^^^^^^^^ this > >> + } else if (entry) { > >> + if (free >= minlen) { > >> + fat_issue_discard(sb, entry, free); > >> + trimmed += free; > >> + } > >> + if (count >= len) > >> + goto done; ^^^^^^^^^^^^^^^^^^ and this > >> + free = 0; > >> + entry = 0; > >> + } > > > > I don't not see why you are testing count all the time since it has not been > > changed since the "if" condition started. how about doing one test > > before the "if" condition ? > > For looping the whole fat max_cluster size. now start can be any > address and if start is a middle point and len is max, then it will > search from middle -> end -> start -> middle. The "count" is used for > this purpose. > > Thank you, > Kyungmin Park > > can go here -->> if (count >= len) goto done; > >> + 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..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; > >> + > >> + range.minlen = max((unsigned int)range.minlen, > >> + q->limits.discard_granularity); > >> + 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 */ > >> } > >> > > > > -- > > > --
