1 files changed, 195 insertions, 39 deletions

diff --git a/fs/fat/fatent.c b/fs/fat/fatent.c
index 1d9a8c4e9de0..a7061c2ad8e4 100644
--- a/fs/fat/fatent.c
+++ b/fs/fat/fatent.c
@@ -1,9 +1,11 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * Copyright (C) 2004, OGAWA Hirofumi
- * Released under GPL v2.
  */
 
 #include <linux/blkdev.h>
+#include <linux/sched/signal.h>
+#include <linux/backing-dev-defs.h>
 #include "fat.h"
 
 struct fatent_operations {
@@ -23,7 +25,7 @@ static void fat12_ent_blocknr(struct super_block *sb, int entry,
 {
 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
 	int bytes = entry + (entry >> 1);
-	WARN_ON(entry < FAT_START_ENT || sbi->max_cluster <= entry);
+	WARN_ON(!fat_valid_entry(sbi, entry));
 	*offset = bytes & (sb->s_blocksize - 1);
 	*blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits);
 }
@@ -33,7 +35,7 @@ static void fat_ent_blocknr(struct super_block *sb, int entry,
 {
 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
 	int bytes = (entry << sbi->fatent_shift);
-	WARN_ON(entry < FAT_START_ENT || sbi->max_cluster <= entry);
+	WARN_ON(!fat_valid_entry(sbi, entry));
 	*offset = bytes & (sb->s_blocksize - 1);
 	*blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits);
 }
@@ -92,7 +94,8 @@ static int fat12_ent_bread(struct super_block *sb, struct fat_entry *fatent,
 err_brelse:
 	brelse(bhs[0]);
 err:
-	fat_msg(sb, KERN_ERR, "FAT read failed (blocknr %llu)", (llu)blocknr);
+	fat_msg_ratelimit(sb, KERN_ERR, "FAT read failed (blocknr %llu)",
+			  (llu)blocknr);
 	return -EIO;
 }
 
@@ -105,8 +108,8 @@ static int fat_ent_bread(struct super_block *sb, struct fat_entry *fatent,
 	fatent->fat_inode = MSDOS_SB(sb)->fat_inode;
 	fatent->bhs[0] = sb_bread(sb, blocknr);
 	if (!fatent->bhs[0]) {
-		fat_msg(sb, KERN_ERR, "FAT read failed (blocknr %llu)",
-		       (llu)blocknr);
+		fat_msg_ratelimit(sb, KERN_ERR, "FAT read failed (blocknr %llu)",
+				  (llu)blocknr);
 		return -EIO;
 	}
 	fatent->nr_bhs = 1;
@@ -289,19 +292,17 @@ void fat_ent_access_init(struct super_block *sb)
 
 	mutex_init(&sbi->fat_lock);
 
-	switch (sbi->fat_bits) {
-	case 32:
+	if (is_fat32(sbi)) {
 		sbi->fatent_shift = 2;
 		sbi->fatent_ops = &fat32_ops;
-		break;
-	case 16:
+	} else if (is_fat16(sbi)) {
 		sbi->fatent_shift = 1;
 		sbi->fatent_ops = &fat16_ops;
-		break;
-	case 12:
+	} else if (is_fat12(sbi)) {
 		sbi->fatent_shift = -1;
 		sbi->fatent_ops = &fat12_ops;
-		break;
+	} else {
+		fat_fs_error(sb, "invalid FAT variant, %u bits", sbi->fat_bits);
 	}
 }
 
@@ -309,7 +310,7 @@ static void mark_fsinfo_dirty(struct super_block *sb)
 {
 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
 
-	if (sb->s_flags & MS_RDONLY || sbi->fat_bits != 32)
+	if (sb_rdonly(sb) || !is_fat32(sbi))
 		return;
 
 	__mark_inode_dirty(sbi->fsinfo_inode, I_DIRTY_SYNC);
@@ -326,7 +327,7 @@ static inline int fat_ent_update_ptr(struct super_block *sb,
 	/* Is this fatent's blocks including this entry? */
 	if (!fatent->nr_bhs || bhs[0]->b_blocknr != blocknr)
 		return 0;
-	if (sbi->fat_bits == 12) {
+	if (is_fat12(sbi)) {
 		if ((offset + 1) < sb->s_blocksize) {
 			/* This entry is on bhs[0]. */
 			if (fatent->nr_bhs == 2) {
@@ -353,9 +354,9 @@ int fat_ent_read(struct inode *inode, struct fat_entry *fatent, int entry)
 	int err, offset;
 	sector_t blocknr;
 
-	if (entry < FAT_START_ENT || sbi->max_cluster <= entry) {
+	if (!fat_valid_entry(sbi, entry)) {
 		fatent_brelse(fatent);
-		fat_fs_error(sb, "invalid access to FAT (entry 0x%08x)", entry);
+		fat_fs_error_ratelimit(sb, "invalid access to FAT (entry 0x%08x)", entry);
 		return -EIO;
 	}
 
@@ -389,10 +390,13 @@ static int fat_mirror_bhs(struct super_block *sb, struct buffer_head **bhs,
 				err = -ENOMEM;
 				goto error;
 			}
+			/* Avoid race with userspace read via bdev */
+			lock_buffer(c_bh);
 			memcpy(c_bh->b_data, bhs[n]->b_data, sb->s_blocksize);
 			set_buffer_uptodate(c_bh);
+			unlock_buffer(c_bh);
 			mark_buffer_dirty_inode(c_bh, sbi->fat_inode);
-			if (sb->s_flags & MS_SYNCHRONOUS)
+			if (sb->s_flags & SB_SYNCHRONOUS)
 				err = sync_dirty_buffer(c_bh);
 			brelse(c_bh);
 			if (err)
@@ -597,7 +601,7 @@ int fat_free_clusters(struct inode *inode, int cluster)
 		}
 
 		if (nr_bhs + fatent.nr_bhs > MAX_BUF_PER_PAGE) {
-			if (sb->s_flags & MS_SYNCHRONOUS) {
+			if (sb->s_flags & SB_SYNCHRONOUS) {
 				err = fat_sync_bhs(bhs, nr_bhs);
 				if (err)
 					goto error;
@@ -612,7 +616,7 @@ int fat_free_clusters(struct inode *inode, int cluster)
 		fat_collect_bhs(bhs, &nr_bhs, &fatent);
 	} while (cluster != FAT_ENT_EOF);
 
-	if (sb->s_flags & MS_SYNCHRONOUS) {
+	if (sb->s_flags & SB_SYNCHRONOUS) {
 		err = fat_sync_bhs(bhs, nr_bhs);
 		if (err)
 			goto error;
@@ -630,20 +634,83 @@ 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 (fatent->entry >= ent_limit)
+		return;
+
+	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;
+
+	/* 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);
+}
 
-	for (i = 0; i < reada_blocks; i++)
-		sb_breadahead(sb, blocknr + i);
+/* 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)
@@ -651,27 +718,20 @@ 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)
@@ -681,6 +741,7 @@ int fat_count_free_clusters(struct super_block *sb)
 			if (ops->ent_get(&fatent) == FAT_ENT_FREE)
 				free++;
 		} while (fat_ent_next(sbi, &fatent));
+		cond_resched();
 	}
 	sbi->free_clusters = free;
 	sbi->free_clus_valid = 1;
@@ -690,3 +751,98 @@ out:
 	unlock_fat(sbi);
 	return err;
 }
+
+static int fat_trim_clusters(struct super_block *sb, u32 clus, u32 nr_clus)
+{
+	struct msdos_sb_info *sbi = MSDOS_SB(sb);
+	return sb_issue_discard(sb, fat_clus_to_blknr(sbi, clus),
+				nr_clus * sbi->sec_per_clus, GFP_NOFS, 0);
+}
+
+int fat_trim_fs(struct inode *inode, struct fstrim_range *range)
+{
+	struct super_block *sb = inode->i_sb;
+	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;
+	int err = 0;
+
+	/*
+	 * FAT data is organized as clusters, trim at the granulary of cluster.
+	 *
+	 * fstrim_range is in byte, convert values to cluster index.
+	 * Treat sectors before data region as all used, not to trim them.
+	 */
+	ent_start = max_t(u64, range->start>>sbi->cluster_bits, FAT_START_ENT);
+	ent_end = ent_start + (range->len >> sbi->cluster_bits) - 1;
+	minlen = range->minlen >> sbi->cluster_bits;
+
+	if (ent_start >= sbi->max_cluster || range->len < sbi->cluster_size)
+		return -EINVAL;
+	if (ent_end >= sbi->max_cluster)
+		ent_end = sbi->max_cluster - 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 */
+		fat_ent_reada(sb, &fatent_ra, &fatent);
+
+		err = fat_ent_read_block(sb, &fatent);
+		if (err)
+			goto error;
+		do {
+			if (ops->ent_get(&fatent) == FAT_ENT_FREE) {
+				free++;
+			} else if (free) {
+				if (free >= minlen) {
+					u32 clus = fatent.entry - free;
+
+					err = fat_trim_clusters(sb, clus, free);
+					if (err && err != -EOPNOTSUPP)
+						goto error;
+					if (!err)
+						trimmed += free;
+					err = 0;
+				}
+				free = 0;
+			}
+		} while (fat_ent_next(sbi, &fatent) && fatent.entry <= ent_end);
+
+		if (fatal_signal_pending(current)) {
+			err = -ERESTARTSYS;
+			goto error;
+		}
+
+		if (need_resched()) {
+			fatent_brelse(&fatent);
+			unlock_fat(sbi);
+			cond_resched();
+			lock_fat(sbi);
+		}
+	}
+	/* handle scenario when tail entries are all free */
+	if (free && free >= minlen) {
+		u32 clus = fatent.entry - free;
+
+		err = fat_trim_clusters(sb, clus, free);
+		if (err && err != -EOPNOTSUPP)
+			goto error;
+		if (!err)
+			trimmed += free;
+		err = 0;
+	}
+
+error:
+	fatent_brelse(&fatent);
+	unlock_fat(sbi);
+
+	range->len = trimmed << sbi->cluster_bits;
+
+	return err;
+}