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fuse: remove fc->blkbits workaround for partial writes

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Now that fuse is integrated with iomap for read/readahead, we can remove
the workaround that was added in commit bd24d2108e ("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>
Tested-by: syzbot@syzkaller.appspotmail.com
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Joanne Koong
2025-09-25 17:26:09 -07:00
committed by Christian Brauner
parent 4ea907108a
commit 93570c652b
3 changed files with 2 additions and 21 deletions
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2
fs/fuse/dir.c
View File

@@ -1192,7 +1192,7 @@ 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;
}

8
fs/fuse/fuse_i.h
View File

@@ -981,14 +981,6 @@ 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;
};
/*

13
fs/fuse/inode.c
View File

@@ -291,7 +291,7 @@ 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
@@ -1838,22 +1838,11 @@ 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
fc->sync_fs = 1;
} else {
sb->s_blocksize = PAGE_SIZE;
sb->s_blocksize_bits = PAGE_SHIFT;
fc->blkbits = sb->s_blocksize_bits;
}
sb->s_subtype = ctx->subtype;