From 76cb841cb886eef6b3bee341a2266c76578724ad Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Mon, 6 May 2024 03:02:30 +0200 Subject: Adding upstream version 4.19.249. Signed-off-by: Daniel Baumann --- fs/fat/fatent.c | 799 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 799 insertions(+) create mode 100644 fs/fat/fatent.c (limited to 'fs/fat/fatent.c') diff --git a/fs/fat/fatent.c b/fs/fat/fatent.c new file mode 100644 index 000000000..5e35307a3 --- /dev/null +++ b/fs/fat/fatent.c @@ -0,0 +1,799 @@ +/* + * Copyright (C) 2004, OGAWA Hirofumi + * Released under GPL v2. + */ + +#include +#include +#include "fat.h" + +struct fatent_operations { + void (*ent_blocknr)(struct super_block *, int, int *, sector_t *); + void (*ent_set_ptr)(struct fat_entry *, int); + int (*ent_bread)(struct super_block *, struct fat_entry *, + int, sector_t); + int (*ent_get)(struct fat_entry *); + void (*ent_put)(struct fat_entry *, int); + int (*ent_next)(struct fat_entry *); +}; + +static DEFINE_SPINLOCK(fat12_entry_lock); + +static void fat12_ent_blocknr(struct super_block *sb, int entry, + int *offset, sector_t *blocknr) +{ + struct msdos_sb_info *sbi = MSDOS_SB(sb); + int bytes = entry + (entry >> 1); + WARN_ON(!fat_valid_entry(sbi, entry)); + *offset = bytes & (sb->s_blocksize - 1); + *blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits); +} + +static void fat_ent_blocknr(struct super_block *sb, int entry, + int *offset, sector_t *blocknr) +{ + struct msdos_sb_info *sbi = MSDOS_SB(sb); + int bytes = (entry << sbi->fatent_shift); + WARN_ON(!fat_valid_entry(sbi, entry)); + *offset = bytes & (sb->s_blocksize - 1); + *blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits); +} + +static void fat12_ent_set_ptr(struct fat_entry *fatent, int offset) +{ + struct buffer_head **bhs = fatent->bhs; + if (fatent->nr_bhs == 1) { + WARN_ON(offset >= (bhs[0]->b_size - 1)); + fatent->u.ent12_p[0] = bhs[0]->b_data + offset; + fatent->u.ent12_p[1] = bhs[0]->b_data + (offset + 1); + } else { + WARN_ON(offset != (bhs[0]->b_size - 1)); + fatent->u.ent12_p[0] = bhs[0]->b_data + offset; + fatent->u.ent12_p[1] = bhs[1]->b_data; + } +} + +static void fat16_ent_set_ptr(struct fat_entry *fatent, int offset) +{ + WARN_ON(offset & (2 - 1)); + fatent->u.ent16_p = (__le16 *)(fatent->bhs[0]->b_data + offset); +} + +static void fat32_ent_set_ptr(struct fat_entry *fatent, int offset) +{ + WARN_ON(offset & (4 - 1)); + fatent->u.ent32_p = (__le32 *)(fatent->bhs[0]->b_data + offset); +} + +static int fat12_ent_bread(struct super_block *sb, struct fat_entry *fatent, + int offset, sector_t blocknr) +{ + struct buffer_head **bhs = fatent->bhs; + + WARN_ON(blocknr < MSDOS_SB(sb)->fat_start); + fatent->fat_inode = MSDOS_SB(sb)->fat_inode; + + bhs[0] = sb_bread(sb, blocknr); + if (!bhs[0]) + goto err; + + if ((offset + 1) < sb->s_blocksize) + fatent->nr_bhs = 1; + else { + /* This entry is block boundary, it needs the next block */ + blocknr++; + bhs[1] = sb_bread(sb, blocknr); + if (!bhs[1]) + goto err_brelse; + fatent->nr_bhs = 2; + } + fat12_ent_set_ptr(fatent, offset); + return 0; + +err_brelse: + brelse(bhs[0]); +err: + 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) +{ + 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_ratelimit(sb, KERN_ERR, "FAT read failed (blocknr %llu)", + (llu)blocknr); + return -EIO; + } + fatent->nr_bhs = 1; + ops->ent_set_ptr(fatent, offset); + return 0; +} + +static int fat12_ent_get(struct fat_entry *fatent) +{ + u8 **ent12_p = fatent->u.ent12_p; + int next; + + spin_lock(&fat12_entry_lock); + if (fatent->entry & 1) + next = (*ent12_p[0] >> 4) | (*ent12_p[1] << 4); + else + next = (*ent12_p[1] << 8) | *ent12_p[0]; + spin_unlock(&fat12_entry_lock); + + next &= 0x0fff; + if (next >= BAD_FAT12) + next = FAT_ENT_EOF; + return next; +} + +static int fat16_ent_get(struct fat_entry *fatent) +{ + int next = le16_to_cpu(*fatent->u.ent16_p); + WARN_ON((unsigned long)fatent->u.ent16_p & (2 - 1)); + if (next >= BAD_FAT16) + next = FAT_ENT_EOF; + return next; +} + +static int fat32_ent_get(struct fat_entry *fatent) +{ + int next = le32_to_cpu(*fatent->u.ent32_p) & 0x0fffffff; + WARN_ON((unsigned long)fatent->u.ent32_p & (4 - 1)); + if (next >= BAD_FAT32) + next = FAT_ENT_EOF; + return next; +} + +static void fat12_ent_put(struct fat_entry *fatent, int new) +{ + u8 **ent12_p = fatent->u.ent12_p; + + if (new == FAT_ENT_EOF) + new = EOF_FAT12; + + spin_lock(&fat12_entry_lock); + if (fatent->entry & 1) { + *ent12_p[0] = (new << 4) | (*ent12_p[0] & 0x0f); + *ent12_p[1] = new >> 4; + } else { + *ent12_p[0] = new & 0xff; + *ent12_p[1] = (*ent12_p[1] & 0xf0) | (new >> 8); + } + spin_unlock(&fat12_entry_lock); + + mark_buffer_dirty_inode(fatent->bhs[0], fatent->fat_inode); + if (fatent->nr_bhs == 2) + mark_buffer_dirty_inode(fatent->bhs[1], fatent->fat_inode); +} + +static void fat16_ent_put(struct fat_entry *fatent, int new) +{ + if (new == FAT_ENT_EOF) + new = EOF_FAT16; + + *fatent->u.ent16_p = cpu_to_le16(new); + mark_buffer_dirty_inode(fatent->bhs[0], fatent->fat_inode); +} + +static void fat32_ent_put(struct fat_entry *fatent, int new) +{ + WARN_ON(new & 0xf0000000); + new |= le32_to_cpu(*fatent->u.ent32_p) & ~0x0fffffff; + *fatent->u.ent32_p = cpu_to_le32(new); + mark_buffer_dirty_inode(fatent->bhs[0], fatent->fat_inode); +} + +static int fat12_ent_next(struct fat_entry *fatent) +{ + u8 **ent12_p = fatent->u.ent12_p; + struct buffer_head **bhs = fatent->bhs; + u8 *nextp = ent12_p[1] + 1 + (fatent->entry & 1); + + fatent->entry++; + if (fatent->nr_bhs == 1) { + WARN_ON(ent12_p[0] > (u8 *)(bhs[0]->b_data + + (bhs[0]->b_size - 2))); + WARN_ON(ent12_p[1] > (u8 *)(bhs[0]->b_data + + (bhs[0]->b_size - 1))); + if (nextp < (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1))) { + ent12_p[0] = nextp - 1; + ent12_p[1] = nextp; + return 1; + } + } else { + WARN_ON(ent12_p[0] != (u8 *)(bhs[0]->b_data + + (bhs[0]->b_size - 1))); + WARN_ON(ent12_p[1] != (u8 *)bhs[1]->b_data); + ent12_p[0] = nextp - 1; + ent12_p[1] = nextp; + brelse(bhs[0]); + bhs[0] = bhs[1]; + fatent->nr_bhs = 1; + return 1; + } + ent12_p[0] = NULL; + ent12_p[1] = NULL; + return 0; +} + +static int fat16_ent_next(struct fat_entry *fatent) +{ + const struct buffer_head *bh = fatent->bhs[0]; + fatent->entry++; + if (fatent->u.ent16_p < (__le16 *)(bh->b_data + (bh->b_size - 2))) { + fatent->u.ent16_p++; + return 1; + } + fatent->u.ent16_p = NULL; + return 0; +} + +static int fat32_ent_next(struct fat_entry *fatent) +{ + const struct buffer_head *bh = fatent->bhs[0]; + fatent->entry++; + if (fatent->u.ent32_p < (__le32 *)(bh->b_data + (bh->b_size - 4))) { + fatent->u.ent32_p++; + return 1; + } + fatent->u.ent32_p = NULL; + return 0; +} + +static const struct fatent_operations fat12_ops = { + .ent_blocknr = fat12_ent_blocknr, + .ent_set_ptr = fat12_ent_set_ptr, + .ent_bread = fat12_ent_bread, + .ent_get = fat12_ent_get, + .ent_put = fat12_ent_put, + .ent_next = fat12_ent_next, +}; + +static const struct fatent_operations fat16_ops = { + .ent_blocknr = fat_ent_blocknr, + .ent_set_ptr = fat16_ent_set_ptr, + .ent_bread = fat_ent_bread, + .ent_get = fat16_ent_get, + .ent_put = fat16_ent_put, + .ent_next = fat16_ent_next, +}; + +static const struct fatent_operations fat32_ops = { + .ent_blocknr = fat_ent_blocknr, + .ent_set_ptr = fat32_ent_set_ptr, + .ent_bread = fat_ent_bread, + .ent_get = fat32_ent_get, + .ent_put = fat32_ent_put, + .ent_next = fat32_ent_next, +}; + +static inline void lock_fat(struct msdos_sb_info *sbi) +{ + mutex_lock(&sbi->fat_lock); +} + +static inline void unlock_fat(struct msdos_sb_info *sbi) +{ + mutex_unlock(&sbi->fat_lock); +} + +void fat_ent_access_init(struct super_block *sb) +{ + struct msdos_sb_info *sbi = MSDOS_SB(sb); + + mutex_init(&sbi->fat_lock); + + switch (sbi->fat_bits) { + case 32: + sbi->fatent_shift = 2; + sbi->fatent_ops = &fat32_ops; + break; + case 16: + sbi->fatent_shift = 1; + sbi->fatent_ops = &fat16_ops; + break; + case 12: + sbi->fatent_shift = -1; + sbi->fatent_ops = &fat12_ops; + break; + } +} + +static void mark_fsinfo_dirty(struct super_block *sb) +{ + struct msdos_sb_info *sbi = MSDOS_SB(sb); + + if (sb_rdonly(sb) || sbi->fat_bits != 32) + return; + + __mark_inode_dirty(sbi->fsinfo_inode, I_DIRTY_SYNC); +} + +static inline int fat_ent_update_ptr(struct super_block *sb, + struct fat_entry *fatent, + int offset, sector_t blocknr) +{ + struct msdos_sb_info *sbi = MSDOS_SB(sb); + 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 ((offset + 1) < sb->s_blocksize) { + /* This entry is on bhs[0]. */ + if (fatent->nr_bhs == 2) { + brelse(bhs[1]); + fatent->nr_bhs = 1; + } + } else { + /* This entry needs the next block. */ + if (fatent->nr_bhs != 2) + return 0; + if (bhs[1]->b_blocknr != (blocknr + 1)) + return 0; + } + } + ops->ent_set_ptr(fatent, offset); + return 1; +} + +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); + const struct fatent_operations *ops = sbi->fatent_ops; + int err, offset; + sector_t blocknr; + + if (!fat_valid_entry(sbi, entry)) { + fatent_brelse(fatent); + fat_fs_error(sb, "invalid access to FAT (entry 0x%08x)", entry); + return -EIO; + } + + fatent_set_entry(fatent, entry); + ops->ent_blocknr(sb, entry, &offset, &blocknr); + + if (!fat_ent_update_ptr(sb, fatent, offset, blocknr)) { + fatent_brelse(fatent); + err = ops->ent_bread(sb, fatent, offset, blocknr); + if (err) + return err; + } + return ops->ent_get(fatent); +} + +/* FIXME: We can write the blocks as more big chunk. */ +static int fat_mirror_bhs(struct super_block *sb, struct buffer_head **bhs, + int nr_bhs) +{ + struct msdos_sb_info *sbi = MSDOS_SB(sb); + struct buffer_head *c_bh; + int err, n, copy; + + err = 0; + for (copy = 1; copy < sbi->fats; copy++) { + sector_t backup_fat = sbi->fat_length * copy; + + for (n = 0; n < nr_bhs; n++) { + c_bh = sb_getblk(sb, backup_fat + bhs[n]->b_blocknr); + if (!c_bh) { + 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 & SB_SYNCHRONOUS) + err = sync_dirty_buffer(c_bh); + brelse(c_bh); + if (err) + goto error; + } + } +error: + return err; +} + +int fat_ent_write(struct inode *inode, struct fat_entry *fatent, + int new, int wait) +{ + struct super_block *sb = inode->i_sb; + const struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops; + int err; + + ops->ent_put(fatent, new); + if (wait) { + err = fat_sync_bhs(fatent->bhs, fatent->nr_bhs); + if (err) + return err; + } + return fat_mirror_bhs(sb, fatent->bhs, fatent->nr_bhs); +} + +static inline int fat_ent_next(struct msdos_sb_info *sbi, + struct fat_entry *fatent) +{ + if (sbi->fatent_ops->ent_next(fatent)) { + if (fatent->entry < sbi->max_cluster) + return 1; + } + return 0; +} + +static inline int fat_ent_read_block(struct super_block *sb, + struct fat_entry *fatent) +{ + const struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops; + sector_t blocknr; + int offset; + + fatent_brelse(fatent); + ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr); + return ops->ent_bread(sb, fatent, offset, blocknr); +} + +static void fat_collect_bhs(struct buffer_head **bhs, int *nr_bhs, + struct fat_entry *fatent) +{ + int n, i; + + for (n = 0; n < fatent->nr_bhs; n++) { + for (i = 0; i < *nr_bhs; i++) { + if (fatent->bhs[n] == bhs[i]) + break; + } + if (i == *nr_bhs) { + get_bh(fatent->bhs[n]); + bhs[i] = fatent->bhs[n]; + (*nr_bhs)++; + } + } +} + +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); + 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; + + BUG_ON(nr_cluster > (MAX_BUF_PER_PAGE / 2)); /* fixed limit */ + + lock_fat(sbi); + if (sbi->free_clusters != -1 && sbi->free_clus_valid && + sbi->free_clusters < nr_cluster) { + unlock_fat(sbi); + return -ENOSPC; + } + + err = nr_bhs = idx_clus = 0; + count = FAT_START_ENT; + fatent_init(&prev_ent); + fatent_init(&fatent); + fatent_set_entry(&fatent, sbi->prev_free + 1); + while (count < sbi->max_cluster) { + if (fatent.entry >= sbi->max_cluster) + fatent.entry = FAT_START_ENT; + fatent_set_entry(&fatent, fatent.entry); + err = fat_ent_read_block(sb, &fatent); + if (err) + goto out; + + /* Find the free entries in a block */ + do { + if (ops->ent_get(&fatent) == FAT_ENT_FREE) { + int entry = fatent.entry; + + /* make the cluster chain */ + ops->ent_put(&fatent, FAT_ENT_EOF); + if (prev_ent.nr_bhs) + ops->ent_put(&prev_ent, entry); + + fat_collect_bhs(bhs, &nr_bhs, &fatent); + + sbi->prev_free = entry; + if (sbi->free_clusters != -1) + sbi->free_clusters--; + + cluster[idx_clus] = entry; + idx_clus++; + if (idx_clus == nr_cluster) + goto out; + + /* + * fat_collect_bhs() gets ref-count of bhs, + * so we can still use the prev_ent. + */ + prev_ent = fatent; + } + count++; + if (count == sbi->max_cluster) + break; + } while (fat_ent_next(sbi, &fatent)); + } + + /* Couldn't allocate the free entries */ + sbi->free_clusters = 0; + sbi->free_clus_valid = 1; + err = -ENOSPC; + +out: + unlock_fat(sbi); + mark_fsinfo_dirty(sb); + fatent_brelse(&fatent); + if (!err) { + if (inode_needs_sync(inode)) + err = fat_sync_bhs(bhs, nr_bhs); + if (!err) + err = fat_mirror_bhs(sb, bhs, nr_bhs); + } + for (i = 0; i < nr_bhs; i++) + brelse(bhs[i]); + + if (err && idx_clus) + fat_free_clusters(inode, cluster[0]); + + return err; +} + +int fat_free_clusters(struct inode *inode, int cluster) +{ + 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 buffer_head *bhs[MAX_BUF_PER_PAGE]; + int i, err, nr_bhs; + int first_cl = cluster, dirty_fsinfo = 0; + + nr_bhs = 0; + fatent_init(&fatent); + lock_fat(sbi); + do { + cluster = fat_ent_read(inode, &fatent, cluster); + if (cluster < 0) { + err = cluster; + goto error; + } else if (cluster == FAT_ENT_FREE) { + fat_fs_error(sb, "%s: deleting FAT entry beyond EOF", + __func__); + err = -EIO; + goto error; + } + + if (sbi->options.discard) { + /* + * Issue discard for the sectors we no longer + * care about, batching contiguous clusters + * into one request + */ + 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); + + first_cl = cluster; + } + } + + ops->ent_put(&fatent, FAT_ENT_FREE); + if (sbi->free_clusters != -1) { + sbi->free_clusters++; + dirty_fsinfo = 1; + } + + if (nr_bhs + fatent.nr_bhs > MAX_BUF_PER_PAGE) { + if (sb->s_flags & SB_SYNCHRONOUS) { + err = fat_sync_bhs(bhs, nr_bhs); + if (err) + goto error; + } + err = fat_mirror_bhs(sb, bhs, nr_bhs); + if (err) + goto error; + for (i = 0; i < nr_bhs; i++) + brelse(bhs[i]); + nr_bhs = 0; + } + fat_collect_bhs(bhs, &nr_bhs, &fatent); + } while (cluster != FAT_ENT_EOF); + + if (sb->s_flags & SB_SYNCHRONOUS) { + err = fat_sync_bhs(bhs, nr_bhs); + if (err) + goto error; + } + err = fat_mirror_bhs(sb, bhs, nr_bhs); +error: + fatent_brelse(&fatent); + for (i = 0; i < nr_bhs; i++) + brelse(bhs[i]); + unlock_fat(sbi); + if (dirty_fsinfo) + mark_fsinfo_dirty(sb); + + return err; +} +EXPORT_SYMBOL_GPL(fat_free_clusters); + +/* 128kb is the whole sectors for FAT12 and FAT16 */ +#define FAT_READA_SIZE (128 * 1024) + +static void fat_ent_reada(struct super_block *sb, struct fat_entry *fatent, + unsigned long reada_blocks) +{ + const struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops; + sector_t blocknr; + int i, offset; + + ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr); + + for (i = 0; i < reada_blocks; i++) + sb_breadahead(sb, blocknr + i); +} + +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; + 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); + 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++; + + err = fat_ent_read_block(sb, &fatent); + if (err) + goto out; + + do { + 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; + mark_fsinfo_dirty(sb); + fatent_brelse(&fatent); +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; + u64 ent_start, ent_end, minlen, trimmed = 0; + u32 free = 0; + unsigned long reada_blocks, reada_mask, cur_block = 0; + int err = 0; + + /* + * FAT data is organized as clusters, trim at the granulary of cluster. + * + * fstrim_range is in byte, convert vaules 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; + + reada_blocks = FAT_READA_SIZE >> sb->s_blocksize_bits; + reada_mask = reada_blocks - 1; + + fatent_init(&fatent); + lock_fat(sbi); + fatent_set_entry(&fatent, ent_start); + while (fatent.entry <= ent_end) { + /* 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 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; +} -- cgit v1.2.3