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-rw-r--r--fs/fat/fatent.c259
1 files changed, 206 insertions, 53 deletions
diff --git a/fs/fat/fatent.c b/fs/fat/fatent.c
index 260705c58062..a7061c2ad8e4 100644
--- a/fs/fat/fatent.c
+++ b/fs/fat/fatent.c
@@ -1,12 +1,11 @@
+// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2004, OGAWA Hirofumi
- * Released under GPL v2.
*/
-#include <linux/module.h>
-#include <linux/fs.h>
-#include <linux/msdos_fs.h>
#include <linux/blkdev.h>
+#include <linux/sched/signal.h>
+#include <linux/backing-dev-defs.h>
#include "fat.h"
struct fatent_operations {
@@ -26,7 +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);
}
@@ -36,7 +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);
}
@@ -95,21 +94,22 @@ 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;
}
static int fat_ent_bread(struct super_block *sb, struct fat_entry *fatent,
int offset, sector_t blocknr)
{
- struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
+ const struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
WARN_ON(blocknr < MSDOS_SB(sb)->fat_start);
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;
@@ -249,7 +249,7 @@ static int fat32_ent_next(struct fat_entry *fatent)
return 0;
}
-static struct fatent_operations fat12_ops = {
+static const struct fatent_operations fat12_ops = {
.ent_blocknr = fat12_ent_blocknr,
.ent_set_ptr = fat12_ent_set_ptr,
.ent_bread = fat12_ent_bread,
@@ -258,7 +258,7 @@ static struct fatent_operations fat12_ops = {
.ent_next = fat12_ent_next,
};
-static struct fatent_operations fat16_ops = {
+static const struct fatent_operations fat16_ops = {
.ent_blocknr = fat_ent_blocknr,
.ent_set_ptr = fat16_ent_set_ptr,
.ent_bread = fat_ent_bread,
@@ -267,7 +267,7 @@ static struct fatent_operations fat16_ops = {
.ent_next = fat16_ent_next,
};
-static struct fatent_operations fat32_ops = {
+static const struct fatent_operations fat32_ops = {
.ent_blocknr = fat_ent_blocknr,
.ent_set_ptr = fat32_ent_set_ptr,
.ent_bread = fat_ent_bread,
@@ -292,19 +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);
}
}
@@ -312,7 +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);
@@ -323,13 +321,13 @@ static inline int fat_ent_update_ptr(struct super_block *sb,
int offset, sector_t blocknr)
{
struct msdos_sb_info *sbi = MSDOS_SB(sb);
- struct fatent_operations *ops = sbi->fatent_ops;
+ const struct fatent_operations *ops = sbi->fatent_ops;
struct buffer_head **bhs = fatent->bhs;
/* 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) {
@@ -352,13 +350,13 @@ int fat_ent_read(struct inode *inode, struct fat_entry *fatent, int entry)
{
struct super_block *sb = inode->i_sb;
struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
- struct fatent_operations *ops = sbi->fatent_ops;
+ const struct fatent_operations *ops = sbi->fatent_ops;
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;
}
@@ -392,10 +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)
@@ -410,7 +411,7 @@ int fat_ent_write(struct inode *inode, struct fat_entry *fatent,
int new, int wait)
{
struct super_block *sb = inode->i_sb;
- struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
+ const struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
int err;
ops->ent_put(fatent, new);
@@ -435,7 +436,7 @@ static inline int fat_ent_next(struct msdos_sb_info *sbi,
static inline int fat_ent_read_block(struct super_block *sb,
struct fat_entry *fatent)
{
- struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
+ const struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
sector_t blocknr;
int offset;
@@ -466,7 +467,7 @@ int fat_alloc_clusters(struct inode *inode, int *cluster, int nr_cluster)
{
struct super_block *sb = inode->i_sb;
struct msdos_sb_info *sbi = MSDOS_SB(sb);
- struct fatent_operations *ops = sbi->fatent_ops;
+ const struct fatent_operations *ops = sbi->fatent_ops;
struct fat_entry fatent, prev_ent;
struct buffer_head *bhs[MAX_BUF_PER_PAGE];
int i, count, err, nr_bhs, idx_clus;
@@ -554,7 +555,7 @@ int fat_free_clusters(struct inode *inode, int cluster)
{
struct super_block *sb = inode->i_sb;
struct msdos_sb_info *sbi = MSDOS_SB(sb);
- struct fatent_operations *ops = sbi->fatent_ops;
+ const struct fatent_operations *ops = sbi->fatent_ops;
struct fat_entry fatent;
struct buffer_head *bhs[MAX_BUF_PER_PAGE];
int i, err, nr_bhs;
@@ -600,7 +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;
@@ -615,7 +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;
@@ -633,48 +634,104 @@ 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)
{
- 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)
{
struct msdos_sb_info *sbi = MSDOS_SB(sb);
- struct fatent_operations *ops = sbi->fatent_ops;
+ 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)
@@ -684,6 +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;
@@ -693,3 +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;
+}
generated by cgit (git 2.34.1) at 2025-12-25 11:17:02 +0000