From c5d0287011679d76288c2617c409252245172a32 Mon Sep 17 00:00:00 2001 From: Richard Sharpe Date: Sun, 27 Dec 2015 16:08:05 -0800 Subject: [PATCH] Fix casesensitivity=insensitive deadlock When casesensitivity=insensitive is set for the file system, we can deadlock in a rename if the user uses different case for each path. For example rename("A/some-file.txt", "a/some-file.txt"). The simple test for this is: 1. mkdir some-dir in a ZFS file system 2. touch some-dir/some-file.txt 3. mv Some-dir/some-file.txt some-dir/some-other-file.txt This last request deadlocks trying to relock the i_mutex on the inode for the parent directory. The solution is to use d_add_ci in zpl_lookup if we are on a file system that has the casesensitivity=insensitive attribute set. This patch checks if we are working on a case insensitive file system and if so, allocates storage for the case insensitive name and passes it to zfs_lookup and then calls d_add_ci instead of d_splice_alias. The performance impact seems to be minimal even though we have introduced a kmalloc and kfree in the lookup path. The problem was found when running Microsoft's FSCT against Samba on top of ZFS On Linux. Signed-off-by: Richard Sharpe Signed-off-by: Brian Behlendorf Closes #4136 --- module/zfs/zpl_inode.c | 32 ++++++++++++++++++++++++++++++-- 1 file changed, 30 insertions(+), 2 deletions(-) diff --git a/module/zfs/zpl_inode.c b/module/zfs/zpl_inode.c index e0e8ee3ac..69a5db4da 100644 --- a/module/zfs/zpl_inode.c +++ b/module/zfs/zpl_inode.c @@ -44,13 +44,24 @@ zpl_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags) struct inode *ip; int error; fstrans_cookie_t cookie; + pathname_t *ppn = NULL; + pathname_t pn; + zfs_sb_t *zsb = dentry->d_sb->s_fs_info; if (dlen(dentry) > ZFS_MAXNAMELEN) return (ERR_PTR(-ENAMETOOLONG)); crhold(cr); cookie = spl_fstrans_mark(); - error = -zfs_lookup(dir, dname(dentry), &ip, 0, cr, NULL, NULL); + + /* If we are a case insensitive fs, we need the real name */ + if (zsb->z_case == ZFS_CASE_INSENSITIVE) { + pn.pn_bufsize = ZFS_MAXNAMELEN; + pn.pn_buf = kmem_zalloc(ZFS_MAXNAMELEN, KM_SLEEP); + ppn = &pn; + } + + error = -zfs_lookup(dir, dname(dentry), &ip, 0, cr, NULL, ppn); spl_fstrans_unmark(cookie); ASSERT3S(error, <=, 0); crfree(cr); @@ -63,13 +74,30 @@ zpl_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags) spin_unlock(&dentry->d_lock); if (error) { + if (ppn) + kmem_free(pn.pn_buf, ZFS_MAXNAMELEN); if (error == -ENOENT) return (d_splice_alias(NULL, dentry)); else return (ERR_PTR(error)); } - return (d_splice_alias(ip, dentry)); + /* + * If we are case insensitive, call the correct function + * to install the name. + */ + if (ppn) { + struct dentry *new_dentry; + struct qstr ci_name; + + ci_name.name = pn.pn_buf; + ci_name.len = strlen(pn.pn_buf); + new_dentry = d_add_ci(dentry, ip, &ci_name); + kmem_free(pn.pn_buf, ZFS_MAXNAMELEN); + return (new_dentry); + } else { + return (d_splice_alias(ip, dentry)); + } } void -- 2.40.0