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Revert "fuse: move initialization of fuse_file to fuse_writepages() instead of in callback"

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This reverts commit 672c3b7457.

fuse_writepages() might be called with no dirty pages after all writable
opens were closed.  In this case __fuse_write_file_get() will return NULL
which will trigger the WARNING.

The exact conditions under which this is triggered is unclear and syzbot
didn't find a reproducer yet.

Reported-by: syzbot+217a976dc26ef2fa8711@syzkaller.appspotmail.com
Link: https://lore.kernel.org/all/CAJnrk1aQwfvb51wQ5rUSf9N8j1hArTFeSkHqC_3T-mU6_BCD=A@mail.gmail.com/
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This commit is contained in:
Miklos Szeredi 2024-10-21 10:02:51 +02:00
parent 20121d3f58
commit 184429a17f
1 changed files with 12 additions and 6 deletions
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18
fs/fuse/file.c
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@ -2288,6 +2288,13 @@ static int fuse_writepages_fill(struct folio *folio,
struct folio *tmp_folio;
int err;
if (!data->ff) {
err = -EIO;
data->ff = fuse_write_file_get(fi);
if (!data->ff)
goto out_unlock;
}
if (wpa && fuse_writepage_need_send(fc, &folio->page, ap, data)) {
fuse_writepages_send(data);
data->wpa = NULL;
@ -2351,13 +2358,13 @@ static int fuse_writepages(struct address_space *mapping,
struct writeback_control *wbc)
{
struct inode *inode = mapping->host;
struct fuse_inode *fi = get_fuse_inode(inode);
struct fuse_conn *fc = get_fuse_conn(inode);
struct fuse_fill_wb_data data;
int err;
err = -EIO;
if (fuse_is_bad(inode))
return -EIO;
goto out;
if (wbc->sync_mode == WB_SYNC_NONE &&
fc->num_background >= fc->congestion_threshold)
@ -2365,9 +2372,7 @@ static int fuse_writepages(struct address_space *mapping,
data.inode = inode;
data.wpa = NULL;
data.ff = fuse_write_file_get(fi);
if (!data.ff)
return -EIO;
data.ff = NULL;
err = -ENOMEM;
data.orig_pages = kcalloc(fc->max_pages,
@ -2381,10 +2386,11 @@ static int fuse_writepages(struct address_space *mapping,
WARN_ON(!data.wpa->ia.ap.num_pages);
fuse_writepages_send(&data);
}
if (data.ff)
fuse_file_put(data.ff, false);
kfree(data.orig_pages);
out:
fuse_file_put(data.ff, false);
return err;
}