From bc36dfffd5f3f19edcf85954d93eb0bc45875c37 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Mon, 24 Feb 2020 12:52:17 +0100 Subject: ext2: Silence lockdep warning about reclaim under xattr_sem Lockdep complains about a chain: sb_internal#2 --> &ei->xattr_sem#2 --> fs_reclaim and shrink_dentry_list -> ext2_evict_inode -> ext2_xattr_delete_inode -> down_write(ei->xattr_sem) creating a locking cycle in the reclaim path. This is however a false positive because when we are in ext2_evict_inode() we are the only holder of the inode reference and nobody else should touch xattr_sem of that inode. So we cannot ever block on acquiring the xattr_sem in the reclaim path. Silence the lockdep warning by using down_write_trylock() in ext2_xattr_delete_inode() to not create false locking dependency. Reported-by: "J. R. Okajima" Reviewed-by: Ritesh Harjani Signed-off-by: Jan Kara --- fs/ext2/xattr.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) (limited to 'fs/ext2/xattr.c') diff --git a/fs/ext2/xattr.c b/fs/ext2/xattr.c index 0456bc990b5e..9ad07c7ef0b3 100644 --- a/fs/ext2/xattr.c +++ b/fs/ext2/xattr.c @@ -790,7 +790,15 @@ ext2_xattr_delete_inode(struct inode *inode) struct buffer_head *bh = NULL; struct ext2_sb_info *sbi = EXT2_SB(inode->i_sb); - down_write(&EXT2_I(inode)->xattr_sem); + /* + * We are the only ones holding inode reference. The xattr_sem should + * better be unlocked! We could as well just not acquire xattr_sem at + * all but this makes the code more futureproof. OTOH we need trylock + * here to avoid false-positive warning from lockdep about reclaim + * circular dependency. + */ + if (WARN_ON_ONCE(!down_write_trylock(&EXT2_I(inode)->xattr_sem))) + return; if (!EXT2_I(inode)->i_file_acl) goto cleanup; -- cgit v1.2.3 From 32302085a8d90859c40cf1a5e8313f575d06ec75 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Tue, 17 Mar 2020 12:40:02 +0100 Subject: ext2: fix debug reference to ext2_xattr_cache MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Fix a debug-only build error in ext2/xattr.c: When building without extra debugging, (and with another patch that uses no_printk() instead of for the ext2-xattr debug-print macros, this build error happens: ../fs/ext2/xattr.c: In function ‘ext2_xattr_cache_insert’: ../fs/ext2/xattr.c:869:18: error: ‘ext2_xattr_cache’ undeclared (first use in this function); did you mean ‘ext2_xattr_list’? atomic_read(&ext2_xattr_cache->c_entry_count)); Fix the problem by removing cached entry count from the debug message since otherwise we'd have to export the mbcache structure just for that. Fixes: be0726d33cb8 ("ext2: convert to mbcache2") Reported-by: Randy Dunlap Signed-off-by: Jan Kara --- fs/ext2/xattr.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'fs/ext2/xattr.c') diff --git a/fs/ext2/xattr.c b/fs/ext2/xattr.c index 9ad07c7ef0b3..6d9731b03715 100644 --- a/fs/ext2/xattr.c +++ b/fs/ext2/xattr.c @@ -872,8 +872,7 @@ ext2_xattr_cache_insert(struct mb_cache *cache, struct buffer_head *bh) true); if (error) { if (error == -EBUSY) { - ea_bdebug(bh, "already in cache (%d cache entries)", - atomic_read(&ext2_xattr_cache->c_entry_count)); + ea_bdebug(bh, "already in cache"); error = 0; } } else -- cgit v1.2.3 From 44a52022e7f15cbaab957df1c14f7a4f527ef7cf Mon Sep 17 00:00:00 2001 From: Randy Dunlap Date: Sun, 22 Mar 2020 19:45:41 -0700 Subject: ext2: fix empty body warnings when -Wextra is used MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit When EXT2_ATTR_DEBUG is not defined, modify the 2 debug macros to use the no_printk() macro instead of . This fixes gcc warnings when -Wextra is used: ../fs/ext2/xattr.c:252:42: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body] ../fs/ext2/xattr.c:258:42: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body] ../fs/ext2/xattr.c:330:42: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body] ../fs/ext2/xattr.c:872:45: warning: suggest braces around empty body in an ‘else’ statement [-Wempty-body] I have verified that the only object code change (with gcc 7.5.0) is the reversal of some instructions from 'cmp a,b' to 'cmp b,a'. Link: https://lore.kernel.org/r/e18a7395-61fb-2093-18e8-ed4f8cf56248@infradead.org Signed-off-by: Randy Dunlap Cc: Jan Kara Cc: linux-ext4@vger.kernel.org Signed-off-by: Jan Kara --- fs/ext2/xattr.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'fs/ext2/xattr.c') diff --git a/fs/ext2/xattr.c b/fs/ext2/xattr.c index 6d9731b03715..943cc469f42f 100644 --- a/fs/ext2/xattr.c +++ b/fs/ext2/xattr.c @@ -56,6 +56,7 @@ #include #include +#include #include #include #include @@ -84,8 +85,8 @@ printk("\n"); \ } while (0) #else -# define ea_idebug(f...) -# define ea_bdebug(f...) +# define ea_idebug(inode, f...) no_printk(f) +# define ea_bdebug(bh, f...) no_printk(f) #endif static int ext2_xattr_set2(struct inode *, struct buffer_head *, -- cgit v1.2.3