path: root/Documentation
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authorLinus Torvalds <torvalds@linux-foundation.org>2014-12-10 16:10:49 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2014-12-10 16:10:49 -0800
commitcbfe0de303a55ed96d8831c2d5f56f8131cd6612 (patch)
treeb327762303c6a015421e4077e7c713b8a47a5e0e /Documentation
parentMerge tag 'dlm-3.19' of git://git.kernel.org/pub/scm/linux/kernel/git/teigland/linux-dlm (diff)
parentMerge branch 'iov_iter' into for-next (diff)
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull VFS changes from Al Viro: "First pile out of several (there _definitely_ will be more). Stuff in this one: - unification of d_splice_alias()/d_materialize_unique() - iov_iter rewrite - killing a bunch of ->f_path.dentry users (and f_dentry macro). Getting that completed will make life much simpler for unionmount/overlayfs, since then we'll be able to limit the places sensitive to file _dentry_ to reasonably few. Which allows to have file_inode(file) pointing to inode in a covered layer, with dentry pointing to (negative) dentry in union one. Still not complete, but much closer now. - crapectomy in lustre (dead code removal, mostly) - "let's make seq_printf return nothing" preparations - assorted cleanups and fixes There _definitely_ will be more piles" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (63 commits) copy_from_iter_nocache() new helper: iov_iter_kvec() csum_and_copy_..._iter() iov_iter.c: handle ITER_KVEC directly iov_iter.c: convert copy_to_iter() to iterate_and_advance iov_iter.c: convert copy_from_iter() to iterate_and_advance iov_iter.c: get rid of bvec_copy_page_{to,from}_iter() iov_iter.c: convert iov_iter_zero() to iterate_and_advance iov_iter.c: convert iov_iter_get_pages_alloc() to iterate_all_kinds iov_iter.c: convert iov_iter_get_pages() to iterate_all_kinds iov_iter.c: convert iov_iter_npages() to iterate_all_kinds iov_iter.c: iterate_and_advance iov_iter.c: macros for iterating over iov_iter kill f_dentry macro dcache: fix kmemcheck warning in switch_names new helper: audit_file() nfsd_vfs_write(): use file_inode() ncpfs: use file_inode() kill f_dentry uses lockd: get rid of ->f_path.dentry->d_sb ...
Diffstat (limited to 'Documentation')
5 files changed, 28 insertions, 29 deletions
diff --git a/Documentation/filesystems/debugfs.txt b/Documentation/filesystems/debugfs.txt
index 3a863f692728..88ab81c79109 100644
--- a/Documentation/filesystems/debugfs.txt
+++ b/Documentation/filesystems/debugfs.txt
@@ -140,7 +140,7 @@ file.
struct dentry *parent,
struct debugfs_regset32 *regset);
- int debugfs_print_regs32(struct seq_file *s, struct debugfs_reg32 *regs,
+ void debugfs_print_regs32(struct seq_file *s, struct debugfs_reg32 *regs,
int nregs, void __iomem *base, char *prefix);
The "base" argument may be 0, but you may want to build the reg32 array
diff --git a/Documentation/filesystems/nfs/Exporting b/Documentation/filesystems/nfs/Exporting
index c8f036a9b13f..520a4becb75c 100644
--- a/Documentation/filesystems/nfs/Exporting
+++ b/Documentation/filesystems/nfs/Exporting
@@ -72,24 +72,11 @@ c/ Helper routines to allocate anonymous dentries, and to help attach
DCACHE_DISCONNECTED) dentry is allocated and attached.
In the case of a directory, care is taken that only one dentry
can ever be attached.
- d_splice_alias(inode, dentry) or d_materialise_unique(dentry, inode)
- will introduce a new dentry into the tree; either the passed-in
- dentry or a preexisting alias for the given inode (such as an
- anonymous one created by d_obtain_alias), if appropriate. The two
- functions differ in their handling of directories with preexisting
- aliases:
- d_splice_alias will use any existing IS_ROOT dentry, but it will
- return -EIO rather than try to move a dentry with a different
- parent. This is appropriate for local filesystems, which
- should never see such an alias unless the filesystem is
- corrupted somehow (for example, if two on-disk directory
- entries refer to the same directory.)
- d_materialise_unique will attempt to move any dentry. This is
- appropriate for distributed filesystems, where finding a
- directory other than where we last cached it may be a normal
- consequence of concurrent operations on other hosts.
- Both functions return NULL when the passed-in dentry is used,
- following the calling convention of ->lookup.
+ d_splice_alias(inode, dentry) will introduce a new dentry into the tree;
+ either the passed-in dentry or a preexisting alias for the given inode
+ (such as an anonymous one created by d_obtain_alias), if appropriate.
+ It returns NULL when the passed-in dentry is used, following the calling
+ convention of ->lookup.
Filesystem Issues
diff --git a/Documentation/filesystems/porting b/Documentation/filesystems/porting
index 0f3a1390bf00..fa2db081505e 100644
--- a/Documentation/filesystems/porting
+++ b/Documentation/filesystems/porting
@@ -463,3 +463,11 @@ in your dentry operations instead.
of the in-tree instances did). inode_hash_lock is still held,
of course, so they are still serialized wrt removal from inode hash,
as well as wrt set() callback of iget5_locked().
+ d_materialise_unique() is gone; d_splice_alias() does everything you
+ need now. Remember that they have opposite orders of arguments ;-/
+ f_dentry is gone; use f_path.dentry, or, better yet, see if you can avoid
+ it entirely.
diff --git a/Documentation/filesystems/seq_file.txt b/Documentation/filesystems/seq_file.txt
index 8ea3e90ace07..b797ed38de46 100644
--- a/Documentation/filesystems/seq_file.txt
+++ b/Documentation/filesystems/seq_file.txt
@@ -180,23 +180,19 @@ output must be passed to the seq_file code. Some utility functions have
been defined which make this task easy.
Most code will simply use seq_printf(), which works pretty much like
-printk(), but which requires the seq_file pointer as an argument. It is
-common to ignore the return value from seq_printf(), but a function
-producing complicated output may want to check that value and quit if
-something non-zero is returned; an error return means that the seq_file
-buffer has been filled and further output will be discarded.
+printk(), but which requires the seq_file pointer as an argument.
For straight character output, the following functions may be used:
- int seq_putc(struct seq_file *m, char c);
- int seq_puts(struct seq_file *m, const char *s);
- int seq_escape(struct seq_file *m, const char *s, const char *esc);
+ seq_putc(struct seq_file *m, char c);
+ seq_puts(struct seq_file *m, const char *s);
+ seq_escape(struct seq_file *m, const char *s, const char *esc);
The first two output a single character and a string, just like one would
expect. seq_escape() is like seq_puts(), except that any character in s
which is in the string esc will be represented in octal form in the output.
-There is also a pair of functions for printing filenames:
+There are also a pair of functions for printing filenames:
int seq_path(struct seq_file *m, struct path *path, char *esc);
int seq_path_root(struct seq_file *m, struct path *path,
@@ -209,6 +205,14 @@ root is desired, it can be used with seq_path_root(). Note that, if it
turns out that path cannot be reached from root, the value of root will be
changed in seq_file_root() to a root which *does* work.
+A function producing complicated output may want to check
+ bool seq_has_overflowed(struct seq_file *m);
+and avoid further seq_<output> calls if true is returned.
+A true return from seq_has_overflowed means that the seq_file buffer will
+be discarded and the seq_show function will attempt to allocate a larger
+buffer and retry printing.
Making it all work
diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt
index 20bf204426ca..43ce0507ee25 100644
--- a/Documentation/filesystems/vfs.txt
+++ b/Documentation/filesystems/vfs.txt
@@ -835,7 +835,7 @@ struct file_operations {
ssize_t (*splice_read)(struct file *, struct pipe_inode_info *, size_t, unsigned int);
int (*setlease)(struct file *, long arg, struct file_lock **, void **);
long (*fallocate)(struct file *, int mode, loff_t offset, loff_t len);
- int (*show_fdinfo)(struct seq_file *m, struct file *f);
+ void (*show_fdinfo)(struct seq_file *m, struct file *f);
Again, all methods are called without any locks being held, unless