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fat: support adding multiple clusters

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fat_add_cluster() currently adds only one cluster to a file's chain,
requiring multiple calls when adding more clusters.

Add a fat_alloc_chain() helper that allocates a cluster chain
but only returns the first cluster. Extend fat_add_cluster()
to add multiple clusters in a single call and rename it to
fat_add_clusters() to reflect the new behavior.

Link: https://lore.kernel.org/20261012171106.146243-3-matheus.aalmeida@inf.ufrgs.br
Signed-off-by: Matheus Alves de Almeida <matheus.aalmeida@inf.ufrgs.br>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
This commit is contained in:
Matheus Alves de Almeida 2026-10-12 14:11:05 -03:00 committed by Andrew Morton
parent 930256458a
commit d2febfdc2b
4 changed files with 23 additions and 8 deletions
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3
fs/fat/fat.h
View File

@ -395,6 +395,7 @@ extern int fat_ent_write(struct inode *inode, struct fat_entry *fatent,
int new, int old, int wait);
extern int fat_alloc_clusters(struct inode *inode, int *cluster,
int nr_cluster);
int fat_alloc_chain(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 inode *inode, struct fstrim_range *range);
@ -440,7 +441,7 @@ static inline unsigned long fat_dir_hash(int logstart)
{
return hash_32(logstart, FAT_HASH_BITS);
}
extern int fat_add_cluster(struct inode *inode);
extern int fat_add_clusters(struct inode *inode, int nr_cluster);
/* fat/misc.c */
extern __printf(3, 4) __cold

18
fs/fat/fatent.c
View File

@ -503,7 +503,8 @@ static int fat_flush_bhs(struct super_block *sb, struct buffer_head **bhs,
return 0;
}
int fat_alloc_clusters(struct inode *inode, int *cluster, int nr_cluster)
static int __fat_alloc_clusters(struct inode *inode, int *cluster, int nr_cluster,
bool return_all)
{
struct super_block *sb = inode->i_sb;
struct msdos_sb_info *sbi = MSDOS_SB(sb);
@ -546,7 +547,10 @@ int fat_alloc_clusters(struct inode *inode, int *cluster, int nr_cluster)
if (sbi->free_clusters != -1)
sbi->free_clusters--;
cluster[idx_clus] = entry;
if (return_all)
cluster[idx_clus] = entry;
else if (!idx_clus)
*cluster = entry;
idx_clus++;
if (nr_bhs + fatent.nr_bhs > MAX_BUF_PER_PAGE) {
@ -596,6 +600,16 @@ int fat_alloc_clusters(struct inode *inode, int *cluster, int nr_cluster)
return err;
}
int fat_alloc_clusters(struct inode *inode, int *cluster, int nr_cluster)
{
return __fat_alloc_clusters(inode, cluster, nr_cluster, true);
}
int fat_alloc_chain(struct inode *inode, int *cluster, int nr_cluster)
{
return __fat_alloc_clusters(inode, cluster, nr_cluster, false);
}
int fat_free_clusters(struct inode *inode, int cluster)
{
struct super_block *sb = inode->i_sb;

2
fs/fat/file.c
View File

@ -292,7 +292,7 @@ static long fat_fallocate(struct file *file, int mode,
/* Start the allocation.We are not zeroing out the clusters */
while (nr_cluster-- > 0) {
err = fat_add_cluster(inode);
err = fat_add_clusters(inode, 1);
if (err)
goto error;
}

8
fs/fat/inode.c
View File

@ -102,16 +102,16 @@ static struct fat_floppy_defaults {
},
};
int fat_add_cluster(struct inode *inode)
int fat_add_clusters(struct inode *inode, int nr_cluster)
{
int err, cluster;
err = fat_alloc_clusters(inode, &cluster, 1);
err = fat_alloc_chain(inode, &cluster, nr_cluster);
if (err)
return err;
/* FIXME: this cluster should be added after data of this
* cluster is writed */
err = fat_chain_add(inode, cluster, 1);
err = fat_chain_add(inode, cluster, nr_cluster);
if (err)
fat_free_clusters(inode, cluster);
return err;
@ -153,7 +153,7 @@ static inline int __fat_get_block(struct inode *inode, sector_t iblock,
*/
if (!offset && !(iblock < last_block)) {
/* TODO: multiple cluster allocation would be desirable. */
err = fat_add_cluster(inode);
err = fat_add_clusters(inode, 1);
if (err)
return err;
}