kernel.git/fs/exfat/dir.c, branch linux-6.10.y

exfat: fix potential deadlock on __exfat_get_dentry_set

2024-08-03T07:00:30Z

commit 89fc548767a2155231128cb98726d6d2ea1256c9 upstream. When accessing a file with more entries than ES_MAX_ENTRY_NUM, the bh-array is allocated in __exfat_get_entry_set. The problem is that the bh-array is allocated with GFP_KERNEL. It does not make sense. In the following cases, a deadlock for sbi->s_lock between the two processes may occur. CPU0 CPU1 ---- ---- kswapd balance_pgdat lock(fs_reclaim) exfat_iterate lock(&sbi->s_lock) exfat_readdir exfat_get_uniname_from_ext_entry exfat_get_dentry_set __exfat_get_dentry_set kmalloc_array ... lock(fs_reclaim) ... evict exfat_evict_inode lock(&sbi->s_lock) To fix this, let's allocate bh-array with GFP_NOFS. Fixes: a3ff29a95fde ("exfat: support dynamic allocate bh for exfat_entry_set_cache") Cc: stable@vger.kernel.org # v6.2+ Reported-by: syzbot+412a392a2cd4a65e71db@syzkaller.appspotmail.com Closes: https://lore.kernel.org/lkml/000000000000fef47e0618c0327f@google.com Signed-off-by: Sungjong Seo Signed-off-by: Namjae Jeon Signed-off-by: Greg Kroah-Hartman

exfat: zero the reserved fields of file and stream extension dentries

2024-04-25T12:59:59Z

From exFAT specification, the reserved fields should initialize to zero and should not use for any purpose. If create a new dentry set in the UNUSED dentries, all fields had been zeroed when allocating cluster to parent directory. But if create a new dentry set in the DELETED dentries, the reserved fields in file and stream extension dentries may be non-zero. Because only the valid bit of the type field of the dentry is cleared in exfat_remove_entries(), if the type of dentry is different from the original(For example, a dentry that was originally a file name dentry, then set to deleted dentry, and then set as a file dentry), the reserved fields is non-zero. So this commit initializes the dentry to 0 before createing file dentry and stream extension dentry. Signed-off-by: Yuezhang Mo Reviewed-by: Andy Wu Reviewed-by: Aoyama Wataru Reviewed-by: Sungjong Seo Signed-off-by: Namjae Jeon

exfat: remove unused functions

2024-03-19T11:56:01Z

exfat_count_ext_entries() is no longer called, remove it. exfat_update_dir_chksum() is no longer called, remove it and rename exfat_update_dir_chksum_with_entry_set() to it. Signed-off-by: Yuezhang Mo Reviewed-by: Andy Wu Reviewed-by: Aoyama Wataru Reviewed-by: Sungjong Seo Signed-off-by: Namjae Jeon

exfat: convert exfat_init_ext_entry() to use dentry cache

2024-03-19T11:55:49Z

Before this conversion, in exfat_init_ext_entry(), to init the dentries in a dentry set, the sync times is equals the dentry number if 'dirsync' or 'sync' is enabled. That affects not only performance but also device life. After this conversion, only needs to be synchronized once if 'dirsync' or 'sync' is enabled. Signed-off-by: Yuezhang Mo Reviewed-by: Andy Wu Reviewed-by: Aoyama Wataru Reviewed-by: Sungjong Seo Signed-off-by: Namjae Jeon

exfat: move free cluster out of exfat_init_ext_entry()

2024-03-19T11:55:45Z

exfat_init_ext_entry() is an init function, it's a bit strange to free cluster in it. And the argument 'inode' will be removed from exfat_init_ext_entry(). So this commit changes to free the cluster in exfat_remove_entries(). Code refinement, no functional changes. Signed-off-by: Yuezhang Mo Reviewed-by: Andy Wu Reviewed-by: Aoyama Wataru Reviewed-by: Sungjong Seo Signed-off-by: Namjae Jeon

exfat: convert exfat_remove_entries() to use dentry cache

2024-03-19T11:55:40Z

Before this conversion, in exfat_remove_entries(), to mark the dentries in a dentry set as deleted, the sync times is equals the dentry numbers if 'dirsync' or 'sync' is enabled. That affects not only performance but also device life. After this conversion, only needs to be synchronized once if 'dirsync' or 'sync' is enabled. Signed-off-by: Yuezhang Mo Reviewed-by: Andy Wu Reviewed-by: Aoyama Wataru Reviewed-by: Sungjong Seo Signed-off-by: Namjae Jeon

exfat: convert exfat_add_entry() to use dentry cache

2024-03-19T11:55:36Z

After this conversion, if "dirsync" or "sync" is enabled, the number of synchronized dentries in exfat_add_entry() will change from 2 to 1. Signed-off-by: Yuezhang Mo Reviewed-by: Andy Wu Reviewed-by: Aoyama Wataru Reviewed-by: Sungjong Seo Signed-off-by: Namjae Jeon

exfat: add exfat_get_empty_dentry_set() helper

2024-03-19T11:55:33Z

This helper is used to lookup empty dentry set. If there are no enough empty dentries at the input location, this helper will return the number of dentries that need to be skipped for the next lookup. Signed-off-by: Yuezhang Mo Reviewed-by: Andy Wu Reviewed-by: Aoyama Wataru Reviewed-by: Sungjong Seo Signed-off-by: Namjae Jeon

exfat: add __exfat_get_dentry_set() helper

2024-03-19T11:55:28Z

Since exfat_get_dentry_set() invokes the validate functions of exfat_validate_entry(), it only supports getting a directory entry set of an existing file, doesn't support getting an empty entry set. To remove the limitation, add this helper. Signed-off-by: Yuezhang Mo Reviewed-by: Andy Wu Reviewed-by: Aoyama Wataru Reviewed-by: Sungjong Seo Signed-off-by: Namjae Jeon

exfat: support create zero-size directory

2023-10-31T01:01:45Z

This commit adds mount option 'zero_size_dir'. If this option enabled, don't allocate a cluster to directory when creating it, and set the directory size to 0. On Windows, a cluster is allocated for a directory when it is created, so the mount option is disabled by default. Signed-off-by: Yuezhang Mo Reviewed-by: Andy Wu Reviewed-by: Aoyama Wataru Signed-off-by: Namjae Jeon