[PATCH 6.1 257/473] ext4: avoid excessive credit estimate in ext4_tmpfile()

Greg Kroah-Hartman
2024-06-06T14:16:13Z

From: Jan Kara <jack@suse.cz>

[ Upstream commit 35a1f12f0ca857fee1d7a04ef52cbd5f1f84de13 ]

A user with minimum journal size (1024 blocks these days) complained
about the following error triggered by generic/697 test in
ext4_tmpfile():

run fstests generic/697 at 2024-02-28 05:34:46
JBD2: vfstest wants too many credits credits:260 rsv_credits:0 max:256
EXT4-fs error (device loop0) in __ext4_new_inode:1083: error 28

Indeed the credit estimate in ext4_tmpfile() is huge.
EXT4_MAXQUOTAS_INIT_BLOCKS() is 219, then 10 credits from ext4_tmpfile()
itself and then ext4_xattr_credits_for_new_inode() adds more credits
needed for security attributes and ACLs. Now the
EXT4_MAXQUOTAS_INIT_BLOCKS() is in fact unnecessary because we've
already initialized quotas with dquot_init() shortly before and so
EXT4_MAXQUOTAS_TRANS_BLOCKS() is enough (which boils down to 3 credits).

Fixes: af51a2ac36d1 ("ext4: ->tmpfile() support")
Signed-off-by: Jan Kara <jack@suse.cz>
Tested-by: Luis Henriques <lhenriques@suse.de>
Tested-by: Disha Goel <disgoel@linux.ibm.com>
Link: https://lore.kernel.org/r/20240307115320.28949-1-jack@suse.cz
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/ext4/namei.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index bbfb37390723c..8b13832238484 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -2901,7 +2901,7 @@ static int ext4_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
inode = ext4_new_inode_start_handle(mnt_userns, dir, mode,
NULL, 0, NULL,
EXT4_HT_DIR,
- EXT4_MAXQUOTAS_INIT_BLOCKS(dir->i_sb) +
+ EXT4_MAXQUOTAS_TRANS_BLOCKS(dir->i_sb) +
4 + EXT4_XATTR_TRANS_BLOCKS);
handle = ext4_journal_current_handle();
err = PTR_ERR(inode);
--
2.43.0