From: Namjae Jeon <linkinjeon@kernel.org>
To: sj1557.seo@samsung.com, yuezhang.mo@sony.com
Cc: linux-fsdevel@vger.kernel.org, anmuxixixi@gmail.com,
dxdt@dev.snart.me, chizhiling@kylinos.cn, hch@lst.de,
Namjae Jeon <linkinjeon@kernel.org>
Subject: [PATCH 4/5] exfat: add support for multi-cluster allocation
Date: Thu, 26 Mar 2026 20:50:44 +0900 [thread overview]
Message-ID: <20260326115045.9525-5-linkinjeon@kernel.org> (raw)
In-Reply-To: <20260326115045.9525-1-linkinjeon@kernel.org>
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.
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
---
fs/exfat/dir.c | 2 +-
fs/exfat/exfat_fs.h | 2 +-
fs/exfat/fatent.c | 26 ++++++++++++++++----------
fs/exfat/file.c | 2 +-
fs/exfat/inode.c | 32 +++++---------------------------
fs/exfat/namei.c | 2 +-
6 files changed, 25 insertions(+), 41 deletions(-)
diff --git a/fs/exfat/dir.c b/fs/exfat/dir.c
index a2c2b998808c..857b22e431cd 100644
--- a/fs/exfat/dir.c
+++ b/fs/exfat/dir.c
@@ -308,7 +308,7 @@ 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;
diff --git a/fs/exfat/exfat_fs.h b/fs/exfat/exfat_fs.h
index 54da001a8f55..5992755b5ab3 100644
--- a/fs/exfat/exfat_fs.h
+++ b/fs/exfat/exfat_fs.h
@@ -448,7 +448,7 @@ int exfat_clear_volume_dirty(struct super_block *sb);
#define exfat_get_next_cluster(sb, pclu) exfat_ent_get(sb, *(pclu), pclu, NULL)
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);
diff --git a/fs/exfat/fatent.c b/fs/exfat/fatent.c
index f2e5d5dde393..758c2d971e73 100644
--- a/fs/exfat/fatent.c
+++ b/fs/exfat/fatent.c
@@ -424,7 +424,7 @@ 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;
@@ -475,14 +475,20 @@ 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--;
+ goto done;
}
- p_chain->flags = ALLOC_FAT_CHAIN;
}
/* update allocation bitmap */
@@ -512,9 +518,9 @@ 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;
}
diff --git a/fs/exfat/file.c b/fs/exfat/file.c
index 5f85e2e0a71e..d7857aec072b 100644
--- a/fs/exfat/file.c
+++ b/fs/exfat/file.c
@@ -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;
diff --git a/fs/exfat/inode.c b/fs/exfat/inode.c
index c53ae9293cfe..46dc98ef1afb 100644
--- a/fs/exfat/inode.c
+++ b/fs/exfat/inode.c
@@ -128,14 +128,10 @@ int exfat_map_cluster(struct inode *inode, unsigned int clu_offset,
struct exfat_sb_info *sbi = EXFAT_SB(sb);
struct exfat_inode_info *ei = EXFAT_I(inode);
unsigned int local_clu_offset = clu_offset;
- unsigned int num_to_be_allocated = 0, num_clusters;
+ unsigned int num_to_be_allocated = *count, num_clusters;
num_clusters = EXFAT_B_TO_CLU(exfat_ondisk_size(inode), sbi);
-
- if (clu_offset >= num_clusters)
- num_to_be_allocated = clu_offset - num_clusters + 1;
-
- if (!create && (num_to_be_allocated > 0)) {
+ if (!create && clu_offset >= num_clusters) {
*clu = EXFAT_EOF_CLUSTER;
return 0;
}
@@ -176,7 +172,7 @@ 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;
@@ -210,26 +206,8 @@ int exfat_map_cluster(struct inode *inode, unsigned int clu_offset,
}
*clu = new_clu.dir;
-
- inode->i_blocks += EXFAT_CLU_TO_B(num_to_be_allocated, sbi) >> 9;
-
- /*
- * 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 (ei->flags == ALLOC_NO_FAT_CHAIN) {
- *clu += num_to_be_allocated - 1;
- } else {
- while (num_to_be_allocated > 1) {
- if (exfat_get_next_cluster(sb, clu))
- return -EIO;
- num_to_be_allocated--;
- }
- }
- *count = 1;
+ *count = new_clu.size;
+ inode->i_blocks += EXFAT_CLU_TO_B(new_clu.size, sbi) >> 9;
*balloc = true;
}
diff --git a/fs/exfat/namei.c b/fs/exfat/namei.c
index d0ea1ff81c09..6261cd994d1d 100644
--- a/fs/exfat/namei.c
+++ b/fs/exfat/namei.c
@@ -347,7 +347,7 @@ 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;
--
2.25.1
next prev parent reply other threads:[~2026-03-26 11:51 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-26 11:50 [PATCH 0/5] exfat: convert to iomap Namjae Jeon
2026-03-26 11:50 ` [PATCH 1/5] exfat: add iomap support Namjae Jeon
2026-03-26 11:50 ` [PATCH 2/5] exfat: add iomap direct I/O support Namjae Jeon
2026-03-26 11:50 ` [PATCH 3/5] exfat: add iomap buffered " Namjae Jeon
2026-03-26 11:50 ` Namjae Jeon [this message]
2026-03-26 11:50 ` [PATCH 5/5] exfat: add support for SEEK_HOLE and SEEK_DATA in llseek Namjae Jeon
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20260326115045.9525-5-linkinjeon@kernel.org \
--to=linkinjeon@kernel.org \
--cc=anmuxixixi@gmail.com \
--cc=chizhiling@kylinos.cn \
--cc=dxdt@dev.snart.me \
--cc=hch@lst.de \
--cc=linux-fsdevel@vger.kernel.org \
--cc=sj1557.seo@samsung.com \
--cc=yuezhang.mo@sony.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox