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exfat: add support for multi-cluster allocation

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Currently exfat_map_cluster() allocates and returns only one cluster
at a time even when more clusters are needed. This causes multiple
FAT walks and repeated allocation calls during large sequential writes
or when using iomap for writes. This change exfat_map_cluster() and
exfat_alloc_cluster() to be able to allocate multiple contiguous
clusters.

Acked-by: Christoph Hellwig <hch@lst.de>
Acked-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
This commit is contained in:
Namjae Jeon 2026-05-07 09:05:08 +09:00
parent a095c12ef1
commit 286ae36887
6 changed files with 26 additions and 31 deletions
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2
fs/exfat/dir.c
View File

@ -295,7 +295,7 @@ int exfat_alloc_new_dir(struct inode *inode, struct exfat_chain *clu)
exfat_chain_set(clu, EXFAT_EOF_CLUSTER, 0, ALLOC_NO_FAT_CHAIN);
ret = exfat_alloc_cluster(inode, 1, clu, IS_DIRSYNC(inode));
ret = exfat_alloc_cluster(inode, 1, clu, IS_DIRSYNC(inode), false);
if (ret)
return ret;

2
fs/exfat/exfat_fs.h
View File

@ -497,7 +497,7 @@ int exfat_clear_volume_dirty(struct super_block *sb);
exfat_cluster_walk(sb, (pclu), 1, ALLOC_FAT_CHAIN)
int exfat_alloc_cluster(struct inode *inode, unsigned int num_alloc,
struct exfat_chain *p_chain, bool sync_bmap);
struct exfat_chain *p_chain, bool sync_bmap, bool contig);
int exfat_free_cluster(struct inode *inode, struct exfat_chain *p_chain);
int exfat_ent_get(struct super_block *sb, unsigned int loc,
unsigned int *content, struct buffer_head **last);

26
fs/exfat/fatent.c
View File

@ -419,7 +419,7 @@ int exfat_zeroed_cluster(struct inode *dir, unsigned int clu)
}
int exfat_alloc_cluster(struct inode *inode, unsigned int num_alloc,
struct exfat_chain *p_chain, bool sync_bmap)
struct exfat_chain *p_chain, bool sync_bmap, bool contig)
{
int ret = -ENOSPC;
unsigned int total_cnt;
@ -470,14 +470,20 @@ int exfat_alloc_cluster(struct inode *inode, unsigned int num_alloc,
while ((new_clu = exfat_find_free_bitmap(sb, hint_clu)) !=
EXFAT_EOF_CLUSTER) {
if (new_clu != hint_clu &&
p_chain->flags == ALLOC_NO_FAT_CHAIN) {
if (exfat_chain_cont_cluster(sb, p_chain->dir,
p_chain->size)) {
ret = -EIO;
goto free_cluster;
if (new_clu != hint_clu) {
if (p_chain->flags == ALLOC_NO_FAT_CHAIN) {
if (exfat_chain_cont_cluster(sb, p_chain->dir,
p_chain->size)) {
ret = -EIO;
goto free_cluster;
}
p_chain->flags = ALLOC_FAT_CHAIN;
}
if (contig && p_chain->size > 0) {
hint_clu = last_clu;
goto done;
}
p_chain->flags = ALLOC_FAT_CHAIN;
}
/* update allocation bitmap */
@ -507,9 +513,9 @@ int exfat_alloc_cluster(struct inode *inode, unsigned int num_alloc,
last_clu = new_clu;
if (p_chain->size == num_alloc) {
done:
sbi->clu_srch_ptr = hint_clu;
sbi->used_clusters += num_alloc;
sbi->used_clusters += p_chain->size;
mutex_unlock(&sbi->bitmap_lock);
return 0;
}

2
fs/exfat/file.c
View File

@ -57,7 +57,7 @@ static int exfat_cont_expand(struct inode *inode, loff_t size)
clu.flags = ei->flags;
ret = exfat_alloc_cluster(inode, new_num_clusters - num_clusters,
&clu, inode_needs_sync(inode));
&clu, inode_needs_sync(inode), false);
if (ret)
return ret;

23
fs/exfat/inode.c
View File

@ -137,9 +137,9 @@ static int exfat_map_cluster(struct inode *inode, unsigned int clu_offset,
unsigned int num_to_be_allocated = 0, num_clusters;
num_clusters = exfat_bytes_to_cluster(sbi, exfat_ondisk_size(inode));
if (clu_offset >= num_clusters)
num_to_be_allocated = clu_offset - num_clusters + 1;
if (clu_offset > num_clusters ||
*count > num_clusters - clu_offset)
num_to_be_allocated = clu_offset + *count - num_clusters;
if (!create && (num_to_be_allocated > 0)) {
*clu = EXFAT_EOF_CLUSTER;
@ -182,7 +182,7 @@ static int exfat_map_cluster(struct inode *inode, unsigned int clu_offset,
}
ret = exfat_alloc_cluster(inode, num_to_be_allocated, &new_clu,
inode_needs_sync(inode));
inode_needs_sync(inode), true);
if (ret)
return ret;
@ -216,20 +216,9 @@ static int exfat_map_cluster(struct inode *inode, unsigned int clu_offset,
}
*clu = new_clu.dir;
*count = new_clu.size;
inode->i_blocks +=
exfat_cluster_to_sectors(sbi, num_to_be_allocated);
/*
* Move *clu pointer along FAT chains (hole care) because the
* caller of this function expect *clu to be the last cluster.
* This only works when num_to_be_allocated >= 2,
* *clu = (the first cluster of the allocated chain) =>
* (the last cluster of ...)
*/
if (exfat_cluster_walk(sb, clu, num_to_be_allocated - 1, ei->flags))
return -EIO;
*count = 1;
inode->i_blocks += exfat_cluster_to_sectors(sbi, new_clu.size);
if (balloc)
*balloc = true;
}

2
fs/exfat/namei.c
View File

@ -341,7 +341,7 @@ int exfat_find_empty_entry(struct inode *inode,
}
/* allocate a cluster */
ret = exfat_alloc_cluster(inode, 1, &clu, IS_DIRSYNC(inode));
ret = exfat_alloc_cluster(inode, 1, &clu, IS_DIRSYNC(inode), false);
if (ret)
return ret;