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Fix errant EFAULT during writes (#8719)

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Commit 98bb45e resolved a deadlock which could occur when
handling a page fault in zfs_write().  This change added
the uio_fault_disable field to the uio structure but failed
to initialize it to B_FALSE.  This uninitialized field would
cause uiomove_iov() to call __copy_from_user_inatomic()
instead of copy_from_user() resulting in unexpected EFAULTs.

Resolve the issue by fully initializing the uio, and clearing
the uio_fault_disable flags after it's used in zfs_write().

Additionally, reorder the uio_t field assignments to match
the order the fields are declared in the  structure.

Reviewed-by: Chunwei Chen <tuxoko@gmail.com>
Reviewed-by: Richard Laager <rlaager@wiktel.com>
Reviewed-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #8640 
Closes #8719
This commit is contained in:
Brian Behlendorf
2019-05-08 10:04:04 -07:00
committed by GitHub
parent 1f02ecc5a5
commit 515ddf6504
4 changed files with 16 additions and 16 deletions
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module/zfs/zpl_inode.c
+2 -3
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@@ -493,7 +493,7 @@ zpl_get_link_common(struct dentry *dentry, struct inode *ip, char **link)
fstrans_cookie_t cookie;
cred_t *cr = CRED();
struct iovec iov;
uio_t uio;
uio_t uio = { { 0 }, 0 };
int error;
crhold(cr);
@@ -503,9 +503,8 @@ zpl_get_link_common(struct dentry *dentry, struct inode *ip, char **link)
uio.uio_iov = &iov;
uio.uio_iovcnt = 1;
uio.uio_skip = 0;
uio.uio_resid = (MAXPATHLEN - 1);
uio.uio_segflg = UIO_SYSSPACE;
uio.uio_resid = (MAXPATHLEN - 1);
cookie = spl_fstrans_mark();
error = -zfs_readlink(ip, &uio, cr);