[PATCH v2 16/16] fuse: remove fc->blkbits workaround for partial writes

Joanne Koong
2025-09-08T18:52:41Z

Now that fuse is integrated with iomap for read/readahead, we can remove
the workaround that was added in commit bd24d2108e9c ("fuse: fix fuseblk
i_blkbits for iomap partial writes"), which was previously needed to
avoid a race condition where an iomap partial write may be overwritten
by a read if blocksize < PAGE_SIZE. Now that fuse does iomap
read/readahead, this is protected against since there is granular
uptodate tracking of blocks, which means this workaround can be removed.

Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
---
fs/fuse/dir.c | 2 +-
fs/fuse/fuse_i.h | 8 --------
fs/fuse/inode.c | 13 +------------
3 files changed, 2 insertions(+), 21 deletions(-)

diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 5c569c3cb53f..ebee7e0b1cd3 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -1199,7 +1199,7 @@ static void fuse_fillattr(struct mnt_idmap *idmap, struct inode *inode,
if (attr->blksize != 0)
blkbits = ilog2(attr->blksize);
else
- blkbits = fc->blkbits;
+ blkbits = inode->i_sb->s_blocksize_bits;

stat->blksize = 1 << blkbits;
}
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index cc428d04be3e..1647eb7ca6fa 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -975,14 +975,6 @@ struct fuse_conn {
/* Request timeout (in jiffies). 0 = no timeout */
unsigned int req_timeout;
} timeout;
-
- /*
- * This is a workaround until fuse uses iomap for reads.
- * For fuseblk servers, this represents the blocksize passed in at
- * mount time and for regular fuse servers, this is equivalent to
- * inode->i_blkbits.
- */
- u8 blkbits;
};

/*
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 7ddfd2b3cc9c..3bfd83469d9f 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -292,7 +292,7 @@ void fuse_change_attributes_common(struct inode *inode, struct fuse_attr *attr,
if (attr->blksize)
fi->cached_i_blkbits = ilog2(attr->blksize);
else
- fi->cached_i_blkbits = fc->blkbits;
+ fi->cached_i_blkbits = inode->i_sb->s_blocksize_bits;

/*
* Don't set the sticky bit in i_mode, unless we want the VFS
@@ -1810,21 +1810,10 @@ int fuse_fill_super_common(struct super_block *sb, struct fuse_fs_context *ctx)
err = -EINVAL;
if (!sb_set_blocksize(sb, ctx->blksize))
goto err;
- /*
- * This is a workaround until fuse hooks into iomap for reads.
- * Use PAGE_SIZE for the blocksize else if the writeback cache
- * is enabled, buffered writes go through iomap and a read may
- * overwrite partially written data if blocksize < PAGE_SIZE
- */
- fc->blkbits = sb->s_blocksize_bits;
- if (ctx->blksize != PAGE_SIZE &&
- !sb_set_blocksize(sb, PAGE_SIZE))
- goto err;
#endif
} else {
sb->s_blocksize = PAGE_SIZE;
sb->s_blocksize_bits = PAGE_SHIFT;
- fc->blkbits = sb->s_blocksize_bits;
}

sb->s_subtype = ctx->subtype;
--
2.47.3